Question

Define the following terms :
(a) Atoms
(b) Molecules
(c) Radicals
(d) Valency
(e) Periodic table​

Answer 1

Answer:

1. Atom: An atom is the smallest indivisible unit of an

OR

Atom is the smallest unit of matter.

2. Molecule : Molecule is the smallest unit of a compound (or an element) which always has an independent existence.

3. Radicals: A radical is an atom of an element or a group of atoms of different elements that behaves as a single unit with a positive or negative charge on it.

4. Valency: It is the number of electrons donated or accepted by the valence shell of an atom during chemical combination.

5. Periodic table represents the tabular arrangement of elements in horizontal rows called periods and vertical columns called groups in order to classify the elements and their systematic study.

Answer 2

Explanation:

(a) Atoms

=>An atom is a particle of matter that uniquely defines achemical element.

• An atom consists of a central nucleus that is usually surrounded by one or more electrons.
• Each electron is negatively charged.
• The nucleus is positively charged, and contains one or more relatively heavy particles known as protons and neutrons.

(b) Molecules

=>A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.

• Molecules are distinguished from ions by their lack of electrical charge.

(c) Radicals

=>a radical is an atom, molecule, or ion that has an unpaired valence electron.

• With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize.
• Most organic radicals have short lifetimes.

(e) Periodic table

=>The periodic table is a tabular array of the chemical elements organized by atomic number, from the element with the lowest atomic number, hydrogen, to the element with the highest atomic number, oganesson.

• The atomic number of an element is the number of protons in the nucleus of an atom of that element.

(d) Valency

=>Valency is the combining power of an element. Elements in the same group of the periodic table have the same valency.

• The valency of an element is related to how many electrons are in the outer shell. Group number.