Language Of Chemistry

Question 1

What is a symbol in chemistry?

Answer 1

A symbol is the shorthand representation for the atom of a specific element.

Question 2

Why is it necessary to represent elements with their symbols?

Answer 2

Symbols provide a quick and efficient way to refer to elements, especially in chemical equations and formulas, making communication easier and more universal.

Question 3

How were the symbols for elements initially derived?

Answer 3

Early symbols were associated with alchemy and the planets. In the 19th century, John Jacob Berzelius systematically assigned the first letter of the element’s name, often from Latin, as its symbol.

Question 4

Which organization approves the names and symbols of elements?

Answer 4

The International Union of Pure and Applied Chemistry (IUPAC) approves the names and symbols of elements.

Question 5

What is valency?

Answer 5

Valency is the combining capacity of an atom or radical with the atoms of other elements to form molecules.

Question 6

How is the valency of an element determined?

Answer 6

The valency of an element is determined by the number of hydrogen atoms it can combine with or displace.

Question 7

What does the modern concept of valency involve?

Answer 7

The modern concept of valency involves the number of electrons lost, gained, or shared by an element to form compounds.

Question 8

What is variable valency?

Answer 8

Variable valency is when an element exhibits more than one valency. For lower valency, the suffix “ous” is used, and for higher valency, the suffix “ic” is used. Nowadays, valencies are written in Roman numbers.

Question 9

What are radicals/ions?

Answer 9

Radicals, also called ions, are atoms or groups of atoms that behave as a single unit with a positive or negative charge.

Question 10

What are acid radicals?

Answer 10

Acid radicals have a negative charge and are also called anions. Examples include most non-metallic ions and groups of non-metallic atoms with a negative charge.

Question 11

What are basic radicals?

Answer 11

Basic radicals have a positive charge and are also called cations. Examples include all metallic ions and ammonium ion.

Question 12

How are the names of simple positive ions derived?

Answer 12

The names of simple positive ions are derived from the names of the parent element. Example: Na^+ is called sodium ion.

Question 13

How are the names of simple negative ions derived?

Answer 13

The names of simple negative ions are derived by replacing the last few letters of the element’s name with the suffix “-ide”. Example: Cl^- is called chloride ion.

Question 14

What suffix is used for polyatomic anions like sulphate and sulphite?

Answer 14

“-ate” is used for higher oxidation states (SO_4^2- is sulphate), and “-ite” is used for lower oxidation states (SO_3^2- is sulphite).

Question 15

What is a molecular formula?

Answer 15

A molecular formula is the symbolic representation of a compound’s molecule, showing the number and types of atoms present in one molecule of that compound.

Question 16

What method is commonly used to write the chemical formula of a compound?

Answer 16

The criss-cross method.

Question 17

What information is needed to write the chemical formula of a compound?

Answer 17

1. Symbols of the elements or radicals that constitute the compound.
2. Valencies or combining capacities of the elements or radicals.

Question 18

What are the significances of the molecular/chemical formula of a compound?

Answer 18

The molecular formula:
1. Represents one molecule of a compound.
2. Shows the elements or ions present in the compound.
3. Indicates the number of each kind of atom and their ratio in one molecule.
4. Allows calculation of the molecular mass by summing the atomic masses of all atoms in the molecule.

Question 19

What is molecular mass?

Answer 19

Molecular mass is the algebraic sum of the masses of all the atoms present in a given molecule.

Question 20

How is the atomic mass of an element determined?

Answer 20

The atomic mass is compared to a standard unit, usually the mass of carbon, and is expressed in atomic mass units (amu).

Question 21

Why is carbon used as the standard for atomic mass?

Answer 21

Carbon is the most widely accepted standard unit for measuring atomic mass because of its stable isotopes and consistent properties.

Question 22

What is a chemical equation?

Answer 22

A chemical equation is a symbolic representation of a chemical reaction using symbols and formulae of the substances involved.

Question 23

What are reactants and products in a chemical equation?

Answer 23

Reactants are the starting materials that react with one another, and products are the substances formed as a result of the reaction.

Question 24

How is a chemical equation written?

Answer 24

Write the symbols or formulae of the reactants on the left side, symbols or formulae of the products on the right side, and use an arrow (→) to separate reactants from products.

Question 25

What does it mean if a chemical equation is balanced?

Answer 25

It means the total number of atoms of each element is equal on both the reactant and product sides of the equation.

Question 26

What is a skeletal equation?

Answer 26

A skeletal equation is an unbalanced chemical equation that shows the reactants and products but does not adhere to the law of conservation of mass. The number of atoms of each element is not equal on both sides of the reaction.

Question 27

Why must chemical equations be balanced?

Answer 27

To ensure that the number of atoms of each element on the reactant side is equal to the number on the product side, in accordance with the law of conservation of mass.

Question 28

What are the significances of a balanced chemical equation?

Answer 28

1) Shows substances involved and products obtained (Qualitative).
2) Indicates the number of molecules and atoms involved (Quantitative).
3) Helps calculate the actual amount of reactants and products.
4) Standardizes chemical study.

Question 29

What does the law of conservation of mass state?

Answer 29

Matter cannot be created or destroyed, only transformed from one form to another.

Question 30

What are the limitations of a chemical equation?

Answer 30

A chemical equation does not inform about:
1. The physical states of reactants and products (solid, liquid, gas).
2. The concentration of reactants and products.
3. The rate at which the reaction proceeds.
4.Heat changes during the reaction (whether heat is absorbed or released).
5.Conditions affecting the reaction (temperature, pressure, catalysts).
6.The nature of the reaction (reversible or irreversible).
7.The time taken for the reaction to complete.

Question 31

How can a chemical equation be made more informative?

Answer 31

A chemical equation can be made more informative by:
1. Indicating the physical state of reactants and products:
- (s) for solid
- (l) for liquid
- (g) for gas
- (aq) for aqueous state
2. Denoting heat evolution or absorption:
- Add or subtract a heat term on the side.
3. Showing temperature, pressure, and catalysts:
- Indicate above the arrow separating reactants and products.
4. Representing concentration:
- Use terms like (dil.) for dilute and (conc.) for concentrated.
5. Depicting reversible reactions:
- Use the sign ↔ to show reversible reactions.

Question 32

What is catalyst?

Answer 32

Catalyst is a substance which increases the rate of a reaction.

Question 33

What’s a promoter?

Answer 33

Promoter is a substance which increases the efficiency of the catalyst.