Question

A. Define the following terms: [7½]

i) Atomic number

ii) Mass number

iii) Orbits

iv) Homo atomic substance

v) Subatomic particles




B. Differentiate between the following: [5]

i) Elements and compound

ii) Electrons and protons

iii) Symbols and formulas

iv) Columns and rows

v) Metalloids and rare gases​

Answer 1

A. define the following terms.

1. atomic number - the number of protons that a chemical element has in its centre.

2.mass number - the total number of protons and neutrons in an atom.

3.orbits - a curved path taken by a planet or another object as it moves around another planet, star, moon, etc.

4.homo atomic substance - the substance which are made up of atoms of the same element. Most of the elementary gases consist of homo atomic molecules. For example hydrogen. gas consists of two atoms of hydrogen (H2).

5.subatomic particles - any of numerous subatomic constituents of the physical world that interact with each other, including electrons, neutrinos, photons, and alpha particles.

B. Differentiate between.

1. elements and compounds - An element refers to a substance that comprises only one type of atom whether A compound refers to a substance that forms due to a combination of two or more elements that are different from one another.
2. electrons and protons - Protons are electrochemically positive in charge and the Neutrons are electrochemically neutral in charge. ... Electrons are electrochemically negatively charged particles that move random around the nucleus.
3. symobls and formulas - Symbols can be defined as the shorthanf notations which represent a single atoms of elements Formula can be defined as the short hand notation which represent a molecule of an element or compound.
4. columns and rows - Rows are a group of cells arranged horizontally to provide uniformity. Columns are a group of cells aligned vertically, and they run from top to bottom.
5. metalliods and rare gases - Metalloids are those substances which have some properties of metals and some of non-metals e.g. boron, silicon.Rare gases are those which do not react chemically with other elements or compounds e.g. helium, neon, etc.

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