Chemical bond & Valency

How many electrons are there in the valence shell of the O^2– ion?

• 2

• 8

• 10

• 6

An atom that loses or gains electrons is called a(n)

• isotope.

• proton.

• neutron.

• ion.

What is the formula of the compound formed between magnesium and oxygen?

• MgO

• Mg₂O₂

• MgO₂

• Mg₂O

Which one of the following elements has valence electrons in the n = 3 shell?

• Beryllium

• Silicon

• Hydrogen

• Neon

Which of the following correctly represents the electronic distribution in the Mg atom? .

• 3, 8, 1

• 2, 8, 2

• 1, 8, 3

• 8, 2, 2

An element has 3 valence electrons in its outermost 3rd shell. The name of the element is ____________.

• B

• Al

• Ga

• In

A symbol represents ____________

• one molecule of an element.

• one ion of an element.

• one atom of an element.

• atomic number of an element.

A molecule of a compound is electrically _______________.

• positive

• negative

• either a) or b)

• neutral

The molecular formula of the compound aluminium sulphate is

• Al(SO₄)₃

• Al₂S₃

• Al₂(SO₃)₃

• Al₂(SO₄)₃

An example of an element which shows variable valency and an element which does not is

• Cu and Fe

• Cu and Sn

• Fe and Al

• Fe and Pb