So4 2- lewis structure - What is usually the first step when drawing a Lewis dot structure? Q. Draw the Lewis structure for CO2− 3. Q. Draw the Lewis dot structure of SN F 3 , consistent with V SEP R . Q. Draw the Lewis dot structure of the following. CO2− 3, HClO4, HN O3. Q. Draw lewis structures for the following molecules HCOOH.CO2− 2.

 
Let us discuss about some important facts about CuSO 4. CuSO4 or copper sulphate is an inorganic salt of copper and sulphate ion. Its molar mass is 159.60 gram/mol. It’s density is 3.6 g/cm3. Copper sulphate has both anhydrous and hydrates form. Most of the common and stable hydrate form found is CuSO4 5 H2O or copper sulphate penta …. Loewe pronunciation

Feb 7, 2021 ... Draw the Lewis structure of the sulfate ion, SO42- How many valence electrons are present? What is. 40 views · 3 years ago ...more ...To illustrate this, let’s take the example of the sulfate ion (SO4^2-). To determine the Lewis structure, we start by counting the total number of valence electrons in the ion. In this case, sulfur contributes 6 valence electrons, while each oxygen atom contributes 6 valence electrons as well.Question: Question 62 of 2 Draw the Lewis structure for sulfate (SD likely resonance structures exist for SO ) with minimized formal charges. How many TOTAL ? Therefore ¿ é å ģô ó ó o. Show transcribed image text. Here’s the best way to solve it.Solution for So4-2 draw the Lewis structure. Types of Chemical Bonds. The attractive force which has the ability of holding various constituent elements like atoms, ions, molecules, etc. together in different chemical species is termed as a chemical bond.Step #1: Calculate the total number of valence electrons. Here, the given molecule is SO (Sulfur monoxide). In order to draw the lewis structure of SO, first of all you have to find the total number of valence electrons present in the SO molecule. (Valence electrons are the number of electrons present in the outermost shell of an atom).Jan 30, 2023 · Resonance is a mental exercise within the Valence Bond Theory of bonding that describes the delocalization of electrons within molecules. It involves constructing multiple Lewis structures that, when combined, represent the full electronic structure of the molecule. Resonance structures are used when a single Lewis structure cannot fully ... Lewis Dot Structures Page ID Learning Objectives Draw the Lewis dot structure of a given molecule or ion. Draw resonance structures of some molecules. Assign formal …Hello Guys!The sulfite ion comprises one Sulfur Atom and three Oxygen atoms. The ion has a negative charge as it accepts two additional electrons. The video ...The 'octet' rule is based upon available n s and n p orbitals for valence electrons (2 electrons in the s orbitals, and 6 in the p orbitals). Beginning with the n=3 principle quantum number, the d orbitals become available ( l =2). The orbital diagram for the valence shell of phosphorous is: Hence, the third period elements occasionally …Simple S N 2 reaction; S N 1 and S N 2; Substrate structure controls substitution mechanism S N 1 or S N 2; Stability and structure of carbocations; S N 2 examples; S N 2 Reaction: Allyl Chloride with HS – S N 2 Reaction: Benzyl Chloride with HS – S N 2 Reaction: 2 o Benzyl Chloride with HS – S N 2' Mechanism; Mitsunobu Reaction ... Working through an Example Lewis Structure Question. Our example is a question on drawing the structure of formaldehyde or H 2 CO. When the question is first opened, a box with a plus symbol is shown below the question. Just click or tap on the plus symbol to open the drawing tool. By default you start with a diatomic molecule with two place ...HPO4 2- Lewis Structure: 3 Easy Step-by-Step Guide. Hydrogen phosphate or HPO42- is the conjugate base of dihydrogen phosphate having molecular weight 95.98 g/mol. It is a divalent inorganic phosphate anion. It has one hydrogen, one phosphate and four oxygen atoms attached by one double bond and three single bonds around the …Which of the following has two or more acceptable Lewis structures? C6H6, HCN, CH3Cl, SO4^2-, UNCl3Watch the full video at:https://www.numerade.com/ask/quest...Jul 19, 2020 ... 376K views · 6:26 · Go to channel · Lewis Structure of SO4(2-) (Sulfate) CORRECT. chemistNATE•618K views · 28:30 · Go to channel...Q. )) View Solution. Click here:point_up_2:to get an answer to your question :writing_hand:according to lewis structure the number of lone pair bond pair of electrons in 5628cf 1.How to Draw the Lewis Dot Structure for SO4 2- (Sulfate ion) Optimizing the Structure. To optimize the Lewis structure, we can rearrange the lone pairs of electrons to minimize formal charges and maximize stability. In the case of SO42-, there is no need for further optimization since all atoms have a formal charge of 0, and the octets …Simple S N 2 reaction; S N 1 and S N 2; Substrate structure controls substitution mechanism S N 1 or S N 2; Stability and structure of carbocations; S N 2 examples; S N 2 Reaction: Allyl Chloride with HS – S N 2 Reaction: Benzyl Chloride with HS – S N 2 Reaction: 2 o Benzyl Chloride with HS – S N 2' Mechanism; Mitsunobu Reaction ... John Lewis is one of the UK’s leading retailers, offering a wide range of products from fashion to home furnishings. With so many products available, it can be difficult to find th...Structured interviews help get relevant and accurate info, which leads to better hires. Here’s the process and some example questions. Human Resources | How To Get Your Free Hiring...Jan 25, 2016 · (O=)_2S(-O^-)_2 There are 5xx6+2 = 32 electrons to distribute over 5 centres (why? because all of the atoms are from Group VI, and thus each has 6 valence electrons, + 2 electrons for the negative charges). Of course this is a resonance structure, in that ALL the sulfur oxygen bonds are equivalent. If we keep (arbitrarily) to the given resonance structure, around each doubly bound oxygen there ... The Lewis dot structure for Cl2, the chemical formula for chlorine gas, is written with two Cl symbols, each of which is surrounded by three pairs of dots, connected by a single li...Jun 6, 2022 ... ... Lewis structure of SO4 2- structure there are a total of 32 valence electrons. ----- Steps to Write Lewis Structure for compounds like SO4 2 ...Jun 13, 2013 · In the Lewis structure of SO4 2- structure there are a total of 32 valence electrons. SO4 2- is also called Sulfate ion. Note that SO4 2- can have an Expanded Octet and have more... Which of the following statement are correct about C O − 2 3? (a) The hybridisation of central atom is s p 3 (b) Its resonance structure has one C - O single bond and two C = 0 double bonds (c) The average formal charge on each oxygen atom is 0.67 units (d) All C - O bond lengths are equalJan 21, 2021 · Lewis Dot Structure of SO4 2- | How to Draw Lewis Structures| Class 11 ChemistryQueries Solved in this videos:-1) lewis structure2) lewis structure chemistry... Nov 27, 2020 · Draw the Lewis structures for the following molecules and ions: H2S, SiCl4, BeF2, CO3^2-, HCOOH. asked Jan 24, 2020 in Chemistry by Nishu03 ( 64.8k points) chemical bonding To use the Lewis Structure Calculator follow these steps: Enter the formula of the molecule in the field provided for it. For example, if we want to obtain the Lewis structure of the Sulfate ion, SO4– 2, we must first enter the charge by typing (-2) or by entering -2 in the charge field and pressing the «Add» button. What is usually the first step when drawing a Lewis dot structure? Q. Draw the Lewis structure for CO2− 3. Q. Draw the Lewis dot structure of SN F 3 , consistent with V SEP R . Q. Draw the Lewis dot structure of the following. CO2− 3, HClO4, HN O3. Q. Draw lewis structures for the following molecules HCOOH.CO2− 2.Sep 15, 2014 ... Comments15 · ESTRUCTURA DE LEWIS Y REGLA DEL OCTETO | Química básica · Lewis Structure of SO4(2-) (Sulfate) CORRECT · Estructuras de Lewis sul...Sulfate is a very weak oxidizing agent. Since sulfur is in its maximum oxidation number in sulfate ion, this ion cannot act as a reducing agent. This page titled Sulfate Ion (SO₄²⁻) is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by James P. Birk. Sulfate ion is a very weak base.Feb 7, 2021 ... Draw the Lewis structure of the sulfate ion, SO42- How many valence electrons are present? What is. 40 views · 3 years ago ...more ...The 'octet' rule is based upon available n s and n p orbitals for valence electrons (2 electrons in the s orbitals, and 6 in the p orbitals). Beginning with the n=3 principle quantum number, the d orbitals become available ( l =2). The orbital diagram for the valence shell of phosphorous is: Hence, the third period elements occasionally …Sep 4, 2022 · How to Draw a Lewis Structure. Step 1: Find the Total Number of Valence Electrons. …. Step 2: Find the Number of Electrons Needed to Make the Atoms “Happy” …. Step 3: Determine the Number of Bonds in the Molecule. …. Step 4: Choose a Central Atom. …. Step 5: Draw a Skeletal Structure. …. Step 6: Place Electrons Around Outside Atoms. Let's do the SO4 2- Lewis structure, for the sulfate ion. On the periodic table: Sulfur, 6 valence electrons; Oxygen also has 6, we have 4 Oxygens, multiply by 4; and these 2 …Mar 20, 2019 · Sulphur cannot form more than four traditional 2-electron-2-centre bonds (double bonds counting as two bonds, triple bonds as three bonds) due to a lack of available orbitals. On a very basic, general and simplified level, such a (localised) 2e2c bond is formed when an orbital of each atom overlap, resulting in a bonding and an antibonding orbital. Hint: For drawing the Lewis structure of any compound or molecule we have to know about the number of valence electrons present in that compound and the valency of each atom present in that compound. Complete step by step answer: For drawing the Lewis structure of Sulfate ion (${\text{SO}}_{\text{4}}^{{\text{2 - }}}$) we have to …The Lewis structure of C2, the chemical formula for diatomic carbon, is written with two Cs connected by two straight lines. Each C also contains one pair of dots, for a total of t...Sulfate is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). E. coli Metabolome Database (ECMDB) Sulfate ion is an Osmotic Laxative. The mechanism of action of sulfate ion is as an Osmotic Activity. The physiologic effect of sulfate ion is by means of Increased Large Intestinal Motility, and Inhibition Large …Jan 6, 2021 · Lewis Structure for sulphate includes an expanded octet for the central sulphur atom.0:00 Lewis structure2:10 Shape and angles3:13 Dipoles5:16 Formal charges... Sep 19, 2013 · Sulfur make six bonds in this Lewis Structure. Two of the oxygens are single-bonded and two are double-bonded. The reason is FORMAL CHARGE and the fact tha... La structure SO4 2- Lewis a un atome de soufre (S) au centre qui est entouré de quatre atomes d’oxygène (O). Il y a 2 liaisons simples et 2 doubles liaisons entre l’atome de Soufre (S) et chaque atome d’Oxygène (O). Il y a 2 paires libres sur les atomes d’oxygène à double liaison (O) et 3 paires libres sur les atomes d’oxygène ...Long Lewis Ford in Hoover, Alabama is the premier destination for anyone looking to buy a car in Birmingham and its surrounding areas. In this article, we will explore why Long Lew...Similarly, the structure of sulphate ions has two negative charges, which means it has two electrons. Sulphur has 6 6 electrons in its valence shell and Lewis dot structure of sulphur gives it two unshared pairs and two unpaired electrons. The structure of sulphate ion is shown below. We can see that two of the oxygen atoms are attached to ...Simple S N 2 reaction; S N 1 and S N 2; Substrate structure controls substitution mechanism S N 1 or S N 2; Stability and structure of carbocations; S N 2 examples; S N 2 Reaction: Allyl Chloride with HS – S N 2 Reaction: Benzyl Chloride with HS – S N 2 Reaction: 2 o Benzyl Chloride with HS – S N 2' Mechanism; Mitsunobu Reaction ... Edit bonds and charges to complete each resonance structure. Draw the Lewis structure of S_2N_2 with formal charges and resonance. Draw Lewis dot structures, including appropriate resonance forms, and assign formal charges to each of those structures, for the molecule urea, with chemical formula NH2CONH2. You should find at leastQ. )) View Solution. Click here:point_up_2:to get an answer to your question :writing_hand:according to lewis structure the number of lone pair bond pair of electrons in 5628cf 1. Hi Everyone! For today’s video, we are going to do SO42- Lewis Structure. It is a chemical formula for Sulfate ions. To determine its Lewis Structure, we fir...How to Draw Lewis Structures in 5 Easy Steps. Gregory Hodgkins (YouTube) Step 1. Count all the valence electrons for each atom. Add or subtract electrons if the structure is an anion or cation, respectively. Example. SO42-. Sulfate is a polyatomic ion with 1 sulfur (6 valence electrons), 4 oxygens (4 x 6 valence electrons = 24 e -) and a charge ...A: Solution- Lewis structure of SbO4-2 ; Q: Write the Lewis structure for each molecule. SiH4. A: Concept introduction: Lewis structure is used to represents the covalent molecule structure with the…. Q: Write the Lewis structure for each molecule. HCOOH (both O bonded to C) Q: In the hypervalent ion ICl3-, the central iodine atom forms ...Oct 29, 2021 · Step 1: Figure out how many electrons the molecule must have, based on the number of valence electrons in each atom. When drawing the structure of an ion, be sure to add/subtract electrons to account for the charge. Step 2: Connect the atoms to each other with single bonds to form a “skeleton structure.”. Following steps are required to draw NO 3- lewis structure and they are explained in detail in this tutorial. Find total number of electrons of the valance shells of nitrogen and oxygen atoms and including charge of the …Jan 3, 2017 · Lewis structure for SO4 (2+) This was a question on a review sheet for Lewis structures. Now I could draw SOX4X2− S O X 4 X 2 − with no issues, but I can't make sense out of SOX4X2+ S O X 4 X 2 + because I can't even make bonds to all O O without exceeding the number of bonding electrons. This is on a high school AP review so it is possible ... The atoms are placed at a 109.5° angle. In order to understand the structure, students can learn to draw the Lewis structure of sulfate and also know about the formal charges and the total number of valence electrons needed for sulfate. Properties of Sulphate. We will discuss some of the physical and chemical properties of sulphate ions below.Solution for So4-2 draw the Lewis structure. Types of Chemical Bonds. The attractive force which has the ability of holding various constituent elements like atoms, ions, molecules, etc. together in different chemical species is termed as a chemical bond.Edit bonds and charges to complete each resonance structure. Draw the Lewis structure of S_2N_2 with formal charges and resonance. Draw Lewis dot structures, including appropriate resonance forms, and assign formal charges to each of those structures, for the molecule urea, with chemical formula NH2CONH2. You should find at leastJul 1, 2013 ... A step-by-step explanation of how to draw the H2SO4 Lewis Structure (Sulfuric Acid). When we have an H (or H2) in front of a polyatomic ...Connect each atom to the central atom with a single bond (one electron pair). Subtract the number of bonding electrons from the total. Distribute the remaining electrons as lone pairs on the terminal atoms (except hydrogen), completing an octet around each atom. Place all remaining electrons on the central atom.The sulphate ion is mainly composed of sulphur and oxygen atoms. Here, sulphur is the central atom, and it is surrounded by four oxygen atoms that are located at equal distances in the plane. For the bonding, 2 of the oxygen atoms form S=O bonds and the other two form S-O- bonds. The oxygen atoms are responsible for the negative charge (-2) of ... To determine the number of lone pairs and bonding pairs of electrons for SO4 2- we first need to draw as valid Lewis Structure. Once we have a Lewis Structur... How To Draw The Lewis Structure of SO4 2- (Sulfate Ion) This chemistry video explains how to draw the lewis structure of the sulfate ion SO4 2-. Chemistry - Basic Introduction: • Chemistry...⇒ Sulphate Ion Formula: SO 4 2-Sulphate is basically a chemical compound that is composed of sulphur and oxygen atoms. Sulphate forms salts with a variety of elements, including potassium, sodium, calcium, …About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright ...Hello Guys!The sulfite ion comprises one Sulfur Atom and three Oxygen atoms. The ion has a negative charge as it accepts two additional electrons. The video ...A step-by-step explanation of how to draw the O3 Lewis Dot Structure (Ozone).For the O3 structure use the periodic table to find the total number of valence ...Sep 23, 2020 ... QUIMICA Estructura de Lewis Sulfato SO4(-2) Expansión Octeto Resonancia AULAEXPRESS. 22K views · 3 years ago ...more ...Question: Question 62 of 2 Draw the Lewis structure for sulfate (SD likely resonance structures exist for SO ) with minimized formal charges. How many TOTAL ? Therefore ¿ é å ģô ó ó o. Show transcribed image text. Here’s the best way to solve it.Nov 1, 2020 ... Comments3 ; Lewis Diagrams Made Easy: How to Draw Lewis Dot Structures. ketzbook · 4.4M views ; Lewis Structure of SO4(2-) (Sulfate) CORRECT.Science. Chemistry. Chemistry questions and answers. lewis structure for SO4 2- ion?Drawing the Lewis Structure for SO 42- ( Sulfate Ion) Sulfates (salts with the SO 42-) are frequently used in industry and biologically. A commonly used sulfate is sodium lauryl ether sulfate found in shampoo, toothpaste, etc. For example, MgSO 4 is also known as Epsom Salts. There are 32 valence electrons available for the Lewis structure for ... This chemistry video tutorial explains how to draw the lewis structure of PO4 3-, the phosphate ion. It also discusses the formal charge and resonance struc...The SO4 2- (Sulfate Ion), comprised of one sulfur atom and four oxygen atoms, presents a captivating example of a chemical species with intriguing properties. At the heart of comprehending the characteristics and reactivity of SO4 2- lies the exploration of its Lewis structure. In this video, you can learn how to draw the Lewis structure of SO4 (2-) ion. For drawing any lewis structure you have to follow some principles or rules:1. ...PH3 e. SO4 2-. Draw the Lewis structure (dot diagram) for each of the following molecules and predict the electron pair geometry and the molecular shape. a. BF3 b. CCl4 c. NO3¯ d. PH3 e. SO4 2-. Here’s the best way to solve it.Jan 6, 2021 · Lewis Structure for sulphate includes an expanded octet for the central sulphur atom.0:00 Lewis structure2:10 Shape and angles3:13 Dipoles5:16 Formal charges... Understanding the Lewis Structure of SO4 2-The first subtitle focuses on explaining the fundamental concepts behind the Lewis structure of the sulfate ion (SO4 2-) in the context of Mathematics education. It aims to provide a clear understanding of how to represent the molecule using Lewis dot diagrams.This problem has been solved! You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: Draw a Lewis structure of sulfate (SO42−) that minimizes charge. Include all electrons and formal charges. Atoms, Bonds and Rings Draw or tap a new bond to see. There’s just one step to solve this.As seen from the above examples, The charge of SO 4 is 2-. In this way, you can easily find the charge of SO4 by looking at what it is bonded to. Method 2: By calculating the formal charge using lewis structure. In order to calculate the formal charge on SO4 (Sulfate ion), you should know the Lewis dot structure of SO4 (Sulfate ion).Dec 1, 2011 · Lewis structures SO4^2- and PO4^3-. Postby Chem_Mod » Thu Dec 01, 2011 11:31 pm. I was wondering why the compound SO4^2- has three Lewis structures whereas PO4^3- has only two. In the book, one of the structures for SO4^2- has 12 electrons attached to the central S-atom. For the Lewis structures for PO4^3-, the most that the P-atom holds is ... A Lewis dot structure for SeO3 is drawn with an Se in the center, with two lines connecting it to two Os and one double line connecting it to an O. The Os connected by single lines...Science. Chemistry. Chemistry questions and answers. lewis structure for SO4 2- ion?When it comes to finding the perfect recliner for your home, John Lewis is a great place to start. With a wide selection of styles and sizes, you’re sure to find something that fit...

SO 4 2-.Lewis Structure (Sulfate ion) Lewis structure of sulfate ion is drawn in this tutorial step by step. Total valence electrons concept is used to draw the lewis structure of SO 4 2-. In lewis structure of sulfate ion, there should be charges on several atoms due to -2 charge. . Symphony of destruction

so4 2- lewis structure

Chủ đề: so4 2- lewis structure: Cấu trúc Lewis của SO4 2- là một cách sắp xếp các nguyên tử và đôi electron trên các nguyên tử để biểu diễn cấu trúc hóa học của ion sulfat. Cấu trúc Lewis này cho phép ta nhìn thấy rõ ràng cách các electron được chia sẻ và phân bố trong phân ... Oct 29, 2015 · SO4 2-. Sulfate ion has two ways of drawing its lewis structure. One is to follow the octet rule and having single bond for each oxygen each perfectly satisfies the octet rule. However, since sulfate can hold more than 8 electrons, it is better to draw the lewis structure with 2 double bond oxygens and 2 single bond oxygens around the sulfur ... Lewis Dot Structure of SO4 2- (Sulfate Ion) kentchemistry.com 25K subscribers Subscribe Subscribed 363 Share 196K views 12 years ago Every Video I quickly take you through …Oct 29, 2021 · Step 1: Figure out how many electrons the molecule must have, based on the number of valence electrons in each atom. When drawing the structure of an ion, be sure to add/subtract electrons to account for the charge. Step 2: Connect the atoms to each other with single bonds to form a “skeleton structure.”. The 'octet' rule is based upon available n s and n p orbitals for valence electrons (2 electrons in the s orbitals, and 6 in the p orbitals). Beginning with the n=3 principle quantum number, the d orbitals become available ( l =2). The orbital diagram for the valence shell of phosphorous is: Hence, the third period elements occasionally …Expert-verified. Answer the following questions about the Lewis structure for gallium (III) sulfate, Ga2 (SO4)3 There are gallium ions and sulfate ions. The central atom in each sulfate is Each sulfate ion has valence electrons, and the central atom has REDs. Each sulfate ion has single covalent bonds, double covalent bonds, and triple covalent ...SO42- Geometry and Hybridization. Sulfur is the central atom: There are 4×6 + 6 + 2 = 32 electrons, and 8 of them are used to make 4 bonds. The four oxygens take 3 lone pairs each and no electrons are left: All the electrons have been used; however, two oxygens need to share a pair of electrons with the sulfur otherwise the ionic would be -4 ...A step-by-step explanation of how to draw the HCO2- Lewis Dot Structure (Formate ion).For the HCO2- structure use the periodic table to find the total number...PO4 3- structure showing Phosphorous at central position. C. Placing the Remaining Atoms. After identifying the central atom, we need to place the remaining atoms around it. In the case of PO4 3-, we have 4 oxygen atoms.Since oxygen needs 2 electrons to complete its octet, we can form a single bond between each oxygen atom and the …The first structure is the best structure. the formal charges are closest to 0 (and also the second structure does not give a complete octet on N) Contributors Paul Flowers (University of North Carolina - Pembroke), Klaus Theopold (University of Delaware) and Richard Langley (Stephen F. Austin State University) with contributing authors.May 6, 2022 · To illustrate this, let’s take the example of the sulfate ion (SO4^2-). To determine the Lewis structure, we start by counting the total number of valence electrons in the ion. In this case, sulfur contributes 6 valence electrons, while each oxygen atom contributes 6 valence electrons as well. The atoms are placed at a 109.5° angle. In order to understand the structure, students can learn to draw the Lewis structure of sulfate and also know about the formal charges and the total number of valence electrons needed for sulfate. Properties of Sulphate. We will discuss some of the physical and chemical properties of sulphate ions below.Oct 14, 2021 · Sulfate is a sulfur oxoanion obtained by deprotonation of both OH groups of sulfuric acid. It has a role as a human metabolite, a Saccharomyces cerevisiae metabolite and a cofactor. It is a sulfur oxoanion, a sulfur oxide, an inorganic anion and a divalent inorganic anion. It is a conjugate base of a hydrogensulfate. ChEBI. Molecular Geometry of NH4. While the Lewis Structure is a 2-dimensional depiction of an atom of a molecule, molecular geometry is the visualization and designing of the atoms in a 3-dimensional space. The concept of molecular geometry aims to depict the generic shape and structure of a molecule, accurate to the length between different …You'll get a detailed solution from a subject matter expert that helps you learn core concepts. Question: Choose the best Lewis structure for SO_4^2. Only one resonance structure is shown (formal charges not shown). Which of the following elements can form expanded octet compounds? N2O, or nitrous oxide, has many Lewis dot structures since both nitrogen and oxygen can act as the center atom. In total, there are three valid Lewis dot structures for nitrous oxi...Downloads expand_more. Download Page (PDF) Download Full Book (PDF) Resources expand_more. Periodic Table. Physics Constants. Scientific Calculator. Reference expand_more. Reference & Cite..

Popular Topics