Topic 1 - Structure and Bonding

Question 1

1. What types of element does ionic bonding occur between?
2. What is the outcome of ionic bonding?

Answer 1

1. One metal and one non-metal
2. Ions are formed.

Question 2

What happens to electrons in ionic bonding?

Answer 2

In ionic bonding electrons and donated and received (Transferred).

Question 3

In ionic bonding diagrams, how do you show:

1. Transferred electrons
2. Ions formed
3. Charge formed

Answer 3

1. Transferred electrons are shown using dots and crosses
2. Formed ions are shown using square brackets
3. Formed charge is shown as a [number]+ or [number]- e.g. 2+ or 2-. The charge is put in the top right outside of the square brackets, and is equal to the amount of electrons the ion needs to gain or lose to go back to normal.

Question 4

What is the force that attracts ions together called?

Answer 4

The oppositely charged ions are attracted to each other by the force of electrostatic attraction.

Question 5

What do you do if one element needs to lose two electrons (e.g. Mg), and the other element only needs to gain one (e.g. Cl)?

Answer 5

You would have just one magnesium ion with a charge of 2-, but you will have two chlorine atoms each with a charge of 1-.

Question 6

What are the 4 positive and 4 negative ions to learn off by heart? What are their ionic formulas?

Answer 6

POSITIVE:
1. Zinc - Zn^2+
2. Silver - Ag^+
3. Hydrogen - H^+
4. Ammonium - NH4^+

NEGATIVE:
1. Nitrate - NO3^-
2. Hydroxide - OH^-
3. Carbonate - CO3^2-
4. Sulfate - SO4^2-

Question 7

What is an ionic compound?

Answer 7

An ionic compound is a giant structure of ions.

Question 8

What are ionic compounds held together by?

Answer 8

Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.

Question 9

What is the arrangement of ions in ionic compounds? What is this arrangement called? Therefore, ionic compounds tend to be what?

Answer 9

The arrangement in ionic compounds is a regular, repeating arrangement, called an ionic lattice. Therefore, ionic compounds tend to be crystalline.

Question 10

1. Do ionic compounds have a high or low melting point? Why?
2. What are ionic compounds level of solubility in water. How does this work?
3. Do ionic compounds conduct electricity? Why?
4. Are ionic compounds brittle? Why?

Answer 10

1. Ionic compounds have a high melting point as lots of energy is needed to overcome the strong electrostatic forces of attraction between the ions.
2. Ionic compounds are soluble in water, this is because water molecules pull ions off the giant ionic lattice and carry them away.
3. Ionic compounds conduct electricity when melted or dissolves as the ions are free to move. However, when solid they do not conduct electricity as the ions can’t move.
4. Ionic crystals tend to be brittle. Any small distortion bring ions of the the same charge in contact with each other, like charges repel and so the crystal splits itself apart.

Question 11

Why are elements in group 8/0 extremely unreactive?

Answer 11

Elements in group 8/0 are unreactive as they already have full outer shells and so don’t need to react to obtain a full outer shell.

Question 12

What types of elements does covalent bonding occur between?

Answer 12

Covalent bonding occurs between two non-metals.

Question 13

What happens to electrons in covalent bonding?

Answer 13

In covalent bonding electrons are shared

Question 14

1. Do covalent compounds have a high or low melting and boiling point? Why?
2. Do covalent compounds conduct electricity? Why?
3. Are covalent compounds brittle? Why?
4. Do covalent compounds dissolve in water?

Answer 14

1. Covalent compounds have a low melting and boiling point as there are weak forces between molecules
2. Covalent compounds don’t conduct electricity as there a no mobile (free) charged particles to carry charge across molecules.
3. Covalent compounds are brittle as there are weak forces between molecules
4. Covalent compounds are insoluble (with some exceptions)

Question 15

What are giant covalent structures?

Answer 15

Substances that consist of giant covalent structures are solid with very high melting points. All the atoms in these structures are linked together by covalent bonds.

Question 16

What are allotropes?

Answer 16

Allotropes are different forms of the same element in the same physical state, but the atoms are bonded differently.

Question 17

What is the structure of diamond, what are it’s properties?

Answer 17

In a diamond, each carbon atom forms four covalent bonds, with other carbon atoms. Diamond is very hard, has a high melting point and does not conduct electricity. Diamonds are clear and colourless.

Question 18

What is the structure of graphite, what are it’s properties?

Answer 18

In graphite, each carbon atom forms three covalent bonds with other carbon atoms. Graphite has a high melting point and is soft. Graphite conducts. Graphite is black and opaque. Layers of graphite can slide past each other.

Question 19

What are the differences in bonding, structure and properties of giant covalents and simple covalents (small molecules)

Answer 19

BONDING: Both have covalent bonds between non-metal atoms.
STRUCTURE: Giant covalent has billions of atoms bonded together. But simple covalents have only a handful of atoms bonded together, with billion held together by inter-molecular forces.
PROPERTY: Giant covalent has a high melting point, but simple covalent has a lower melting point.

Question 20

What is a cation? What is an anion?

Answer 20

A cation is a positively charges ion, an anion is a negatively charged ion.

Question 21

How are the atoms in a pure metal arranged?

Answer 21

Atoms in a pure metal are in tightly packed layers, which form a regular giant structure.

Question 22

What happens to the outer electrons of the metal in metallic bonding? What do we call these electrons?

Answer 22

In metallic bonding the outer electrons separate from the atoms to form a sea of electrons. These electrons are delocalised, meaning they are free to move through the whole structure.

Question 23

What happens to the metal atoms and electrons after?

Answer 23

The metal atoms become positively charged, meaning they are attracted to the negatively charged sea of electrons. This attraction is called metallic bonding.

Question 24

1. Do metallic compounds have a high or low melting and boiling point? Why?
2. Are metallic compound good conductors of electricity and heat? Why?
3. Are metallic compounds malleable and ductile? Why?
4. Are metallic compounds soluble in water?

Answer 24

1. Metallic compounds have high melting points as lots of energy is needed to break the bonds between the atoms.
2. Metallic compound are good conductors of electricity and heat as the delocalised sea of electrons in the metal can carry current through the metal.
3. Metallic compounds are malleable and ductile as layers can slide past each other.
4. Metallic compounds are not soluble in water because water cannot form attraction with the ions.

Question 25

What are the colours in a flame test of the 5 cations in metallic compounds (that we need to know)?

Answer 25

Lithium (Cation) Chloride - Crimson Red
Sodium (Cation) Chloride - Orange/Yellow
Potassium (Cation) Chloride - Lilac
Calcium (Cation) Carbonate - Brick Red
Magnesium (Cation) Carbonate - No colour

Question 26

Why are pure metals soft?

Answer 26

Because the layers of ions can slide past each other while maintaining their metallic bonding.

Question 27

What is an abrasive?

Answer 27

An abrasive is something that can wear away another material.