Ionic bonding

Magnesium chloride, MgCl₂, is an ionic compound. Draw dot-and-cross diagrams for MgCl₂

Sodium and chlorine react together to produce sodium chloride. The bonding in the product is different from that in both of the reactants. Sodium chloride is ionically bonded. 

State the meaning of the term ‘ionic bond’.

The strong force of attraction between the positive and negative ions in the ionic crystal lattice results in an ionic bond. An ionic bond is sometimes called an electrovalent bond.

Using the data sheet, write the formulas of the following compounds: 

i. Barium sulfate

ii. Lithium phosphide

iii. Chromium (III) hydroxide

i. The formula of barium sulfate: BaSO₄

ii. The formula of lithium phosphide: Li₃P

iii. The formula of chromium (III) hydroxide: Cr(OH)₃

Student A and B then went on to discuss the bonding in two other substances, Li₂S and CS₂.

Explain, in terms of electrons, how Li₂S is formed from its atoms.

2 Lithium atoms lose 1 electron for each. Then 1 sulfur atom receives 2 electrons from Li atom forming 2 Li⁺ and 1 S^2-

i. Calcium will react with the elements of Group 7 to form ionic compounds, which have an ionic lattice structure. Describe what is meant by the term ionic lattice.

ii. One example of an ionic compound which calcium forms is calcium chloride. 

Using your knowledge of the structure and bonding of an ionic substance, state whether calcium chloride would have a high or low melting point. Explain your answer.

i. This term refers to a regular pattern and is of positive and negative ions

ii. The melting point is high because there are strong electrostatic forces of attraction in all directions, which leads to a large amount of energy being needed to break down these bonds.

Coal often contains traces of iron (II) disulfide, `FeS_2`. `FeS_2` is an ionic compound of `Fe^(2+`ions and `S""_2^(2-` ions.

i. Write the electron configuration, in terms of sub-shells, of an `Fe^(2+`.

ii. Draw a ‘dot-and-cross’ diagram for `FeS_2`.

Show outer shell electrons only.

i. The electron configuration of `Fe^(2+` is `1s^2 2s^2 2p^6 3s^2 3p^6 3d^6`

ii. 

Which of the following compounds is not bonded ionically?

A. CH₃OH

B. MgCO₃

C. LiOH

D. BaCl₂

The answer is A.

Ionic bonding is the strong force of attraction between the positive and negative ions in the ionic crystal lattice. Ionic bonds generally happens between metals (cations) and nonmetals (anions)

B, C, D are correct because magnesium, lithium and barium are metals and the anion parts are non-metal ions

Element X forms a carbonate with the formula X₂CO₃. Which of these could represent the shorthand electron configuration of an atom of X?

A. [Ne] 3s¹

B. [Ne] 3s²

C. [Ne] 3s¹ 3p²

D. [Ne]

The answer is A.

The formula X₂CO₃ implies that the charge on a X ion is +1 to neutralize the charge overall for this compound. That means that element X must be in a group 1 which is found in s block thus, it will be [Ne] 3s¹

Which one of the following statements about positive ions is incorrect?

A. Also known as cations 

B. Formed when electrons are removed from atoms 

C. Larger than the atom from which they are formed 

D. Smaller than the atom from which they are formed

The answer is C.

A is correct because positive ions are called cations. 

B is correct because  positively charged cations are formed specifically through the removal of electrons. 

C is incorrect because when an electron is lost, there is less electron-electron repulsion and a stronger attraction between the remaining electrons and the nucleus, causing the cation to be smaller than the neutral atom. 

D is correct because cations are always smaller than their corresponding neutral atoms.

Which one of the following pairs atoms is most likely to form an ionic bond?

A. Na and F

B. C and F 

C. N and F 

D. O and F

The answer is A.

Ionic bonding is the strong force of attraction between the positive and negative ions in the ionic crystal lattice. Ionic bonds generally happens between metals (cations) and nonmetals (anions)

B, C, and D are incorrect because molecules are formed between 2 non-metal ions