A. explain what is meant by term

1. atomic numbers

2. periodic pattern

b. 1. state one physical property and one chemical property shared by helium, argon, and neon

2. what is name given to this group of elements?

1. Atomic numbers:

Atomic number is the number of protons in an atom. It is one of the most diagonistic and representative number used in identifying an atom. The periodic table of element arranges elements based on this number.

No two elements have the same atomic number.

Protons are positively charged particles in an atom.

In a neutral atom, the atomic number is the same as the number electrons since electrical neutrality is attained when the number of protons and electrons are the same. The atomic number determines the position of an atom on the periodic table and it is unique for every atom.

2.

Periodic patterns

These are trends on that can be predicted on the periodic table because they shew regularities down a group or sometimes across the period.

Some of these trends are atomic radius, electronegativity, metallicity, nuclear charge e. t. c

Properties of elements can be predicted using these patterns even before they are discovered.

b.

Physical property shared by Helium, Argon and Neon is that they are all gases. All group 8 elements are called noble or inert gases.

Chemical property of these elements: they are chemically unreactive.

These gases are very stable having complete electronic shell configuration. Every atom on the periodic table tries to attain the state of the noble gases.

C.

Noble Gases / Inert Gases / Group O elements