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Chemical formulae of compounds. Chemists use symbols and formulae to represent elements, ions and compounds. Word equations and balanced chemical equations model the changes that happen in ...
There’s a particular way of writing what’s in a molecule called a chemical formula. The chemical formulae for all the elements that form each molecule and uses a small number to the bottom right of an element’s symbol to stand for the number of atoms of that element. For example, the chemical formula for water is H 2 O.
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- The first component in the formula is simply identified with the element name. The second component is named by taking the name of the element stem...
- Hydrogen gas (H 2 ) is a molecule but not a compound because it consists of only one part. Water (H 2 O) can be referred to as a molecule or compou...
- Currently the periodic table includes 118 elements. Some elements were present only in laboratories and in nuclear accelerators. So, you may wonder...
- A molecular formula is not a chemical name, so there are no terms to it. While certain basic chemical structures can be suggested by a molecular fo...
- The formula of a substance, in terms of its atoms and molecules, denotes its composition. For example, ethane has 2 atoms of carbon and 6 atoms of...
write the molecular formula of a compound, given its Kekulé structure. draw the shorthand structure of a compound, given its Kekulé structure. interpret shorthand structures and convert them to Kekulé structures.
- Valency of Ions –
- Writing Formulae of Ionic Compounds –
- Questions About Chemical Formulae from Ncert Textbook –
In order to write the formulae of ionic compounds, we should know the valencies of positive ions and negative ions which combine to form the ionic compounds. The valency of an ion is equal to the charge on the ion. If an ion has 1 unit charge, its valency is 1 and it is called a monovalent ion. If an ion has 2 units of charge, its valency is 2 and ...
To write the formula of ionic compounds, first we write down the name of compound and after that we write the symbols of its ions. As a convention, the cation is written on the left hand side and the anion is written on the left hand side. The number of cations and anions is adjusted in such a way that the total number of positive valencies of cati...
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Question 1:- Write down the formulae of : (i) Sodium oxide (ii) Aluminium chloride (iii) Sodium sulphide (iv) Magnesium hydroxide Answer:- Question 2:- Write down the names of compounds represented by the following formulae: (i) Al2(SO4)3 (ii) CaCl2 (iii) K2SO4 (iv) KNO3 (v) CaCO3 Answer:- (i) Aluminium sulphate (ii) Calcium chloride (iii) Potassium sulphate (iv) Potassium nitrate (v) Calcium carbonate
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Question 4:- Write the chemical formulae of the following : (a) Magnesium chloride (b) Calcium oxide (c) Copper nitrate (d) Aluminium chloride (e) Calcium carbonate Answer :- Writing chemical formulae of a compound is very important because the chemical formula gives identity to the compound. The valencies of elements need to be known to write the chemical formulae. The ionic compounds are divided into monovalent, divalent and trivalent ions on the basis of their valencies. We use a criss-cro...
NCERT Solutions Class 9 Science Chapter 4 Structure of the Atom – Here are all the NCERT solutions for Class 9 Science Chapter 4. This solution contains questions, answers, images, step by step explanations of the complete Chapter 4 titled Structure of the Atom of Science taught in class 9.
Drawing every bond and every atom is tedious, however, so chemists have devised several shorthand ways for writing structures. In condensed structures, carbon– hydrogen and carbon–carbon single bonds aren’t shown; instead, they’re understood.
Balanced chemical equation - A chemical equation in which the number of each type of atom is equal on the two sides of the equation. Subscripts - Part of the chemical formulas of the reactants and products that indicate the number of atoms of the preceding element.
