Chemistry chapter 3

What is the periodic law?

‘Elements have properties that recur or repeat according to their atomic number’

What is the relative atomic mass?

Protons + neutrons

What is responsible for most of the mass of the atom?

Subatomic particles (protons and neutrons)

What is the number of protons called?

Atomic number

Why are alkali metals highly reactive?

Because they have a single electron in their outer shell. (e.g. 2,8,1)

Do alkaline earth metals have low or high melting points?

low

Do alkali metals have low or high melting points?

High

Are alkali and alkaline earth metals soft and reactive?

Yes

Where are non-metals found in the periodic table?

group 14-18

Are non-metals brittle?

Yes

Are metals brittle?

usually no

What do metals form when they lose electrons and why?

Cations(+) to achieve a full, stable valency shell.

What do non-metals form when they gain electrons and why?

Anions to achieve a full, stable valency shell.

When is an atom referred to as an ion?

When it gains or looses an electron

What is a polyatomic ion?

Ion made of 2 or more atoms that are bonded and have a charge.

What’s a diatomic molecule?

2 atoms bonded together.

What’s a molecular compound?

2 or more non-metal atoms joined by covalent bonds.

What state are most molecular substances at room temperature?

Most are liquids or gases due to weak forces between molecules.