Chemical Bonding

The symbol for a calcium ion is ..................

When an atom forms a negative ion, it ................................

Answer explanation

To form a negative ion, the atom needs to gain electrons.

How many electrons and protons are present in N^3- ion?

• proton: 7

  electron: 7

• proton: 7

  electron: 10

• proton: 10

  electron: 7

• proton: 10

  electron: 10

Answer explanation

The proton number of nitrogen is 7 and it has the electronic configuration of 2,5.

Nitrogen needs 3 more electrons to achieve stable electronic configuration of noble gas.

The options below show the electronic configuration of four different atoms.

Which atom would form an ion with a positive charge?

• 2,5

• 2,8,3

• 2,8,7

• 2,8,8

Answer explanation

To form a positive ion, the atom must lose the valence electron.

Which statement is false about ionic bonding?

• It involves the sharing of electrons

• It is the attraction between oppositely charged ions.

• The compound has ionic lattice structure.

• It involves the transferring of electrons.

Which two statements about a covalent bond are correct?

I - It can be formed between two non-metal atoms.

II - It can be formed between two metal atoms.

III - It is formed by transferring electrons between atoms.

IV - It is formed by sharing electrons between atoms.

• I and III

• I and IV

• II and III

• II and IV

The table shows the electron arrangement in four atoms.

The two atoms which will form an ionic compound are ...................................

Answer explanation

W is a metal as it has 1 valence electron. It is placed in Group I.

X is a non-metal as it has 8 valence electrons. It is placed in Group 0. However this atom does not share or give away or take in electrons.

Y is a non-metal as it has 5 valence electrons. It is placed in Group V.

Z is a non-metal as it has 7 valence electrons. It is placed in Group VII.

Ionic compound is formed between metal and non-metal atoms.

The electronic structures of atoms X and Y are shown.

X and Y react to form a covalent compound.

What is its formula?

• XY

• XY₂

• X₂Y

• X₂Y₂

Answer explanation

X needs 2 more electrons to achieve stable electronic configuration of noble gas.

Y needs 1 more electron to achieve stable electronic configuration of noble gas.