Unit 1, Topic 3 - Bonding and Structure

Question 1

What types of substances usually form together to make ionic compounds?

Answer 1

Metal and non-metal

Question 2

Describe ionic bonding

Answer 2

It is an electrostatic force of attraction between oppositely charged ions.

Question 3

What can be said about the strength of ionic bonds?

Answer 3

They are strong

Question 4

Why do atoms gain or lose electrons?

Answer 4

They are more stable with a full outer shell of electrons. When forming compounds atoms tend to have stable electron arrangement.

Question 5

How do you work out how many electrons a metal loses when it forms an ion?

Answer 5

A metal loses electrons equal to the number of electrons in the outer shell.

Question 6

A metal loses electrons equal to the number of electrons in the outer shell.
Why do metal ions do this?

Answer 6

They are more stable with a full outer shell of electrons.

Question 7

What always happens when metal atoms form ions?

Answer 7

They lose electrons to form positive ions.

Question 8

Write an equation to show how aluminium ions are formed from aluminium atoms.

Answer 8

Al —> Al 3+ + 3e-
2,8,3 2,8

Question 9

What happens to non-metal atoms when they form ions?

Answer 9

They always gain electrons to become negative ions.

Question 10

How do you work out how many electrons a non-metal atom gains when it forms an ion?

Answer 10

The number of electrons gained is the same as the number of electrons needed to fill the outer shell.

Question 11

Know how to write nuclide notation for ions. E.g. How would you write the nuclide notation for a chloride ion with mass number 35?

Answer 11

35
Cl-
17

Question 12

Know how to work out the number of protons, neutrons and electrons when given the nuclide notation of an ion. E.g. 27
Al 3+
13

Answer 12

protons+13
neutrons+14
electrons=10

Question 13

What type of substances have metallic bonding?

Answer 13

Metals

Question 14

Describe metallic bonding.

Answer 14

Electrostatic attraction between positively charged atom cores or ions and delocalised electrons.

Question 15

What can be said about the strength of a metallic bond?

Answer 15

It is strong

Question 16

What type of elements usually form covalent compounds?

Answer 16

Non-metal atoms

Question 17

What is a covalent bond?

Answer 17

A shared pair of electrons

Question 18

What holds the atoms together in covalent bonding?
(be able to draw diagrams)

Answer 18

The shared pair of electrons is attracted to both positive nuclei.

Question 19

Be able to draw diagrams to show howthe outer electrons are shared in elements and compounds to from covalent bonds.

Answer 19

See notes and slides.

Question 20

What is the formula for an oxygen molecule? How many bonds are there between atoms?

Answer 20

O2-2 shared pairs of electrons (we write the 2 smaller and at the bottom of the O.

Question 20

What is a diatomic molecule?

Answer 20

A molecule that contains 2 atoms

Question 21

What is a molecule?

Answer 21

A group of atoms held together by covalent bonds.

Question 22

What are the 7 elements that exist as a diatomic molecule?

Answer 22

H2, O2, N2, F2, Cl2, Br2, I2

Question 22

Which of the following molecules are diatomic?
HCl, H2O,NH3, CO, CO2

(be able to identify compounds that exist as diatomic molecules)

Answer 22

CO and HCl

Question 23

What shape are diatomic molecules?

Answer 23

Linear

Question 23

Look at LI 24-27

Answer 23

for drawing the shape of atom molecules.

Question 23

What is meant by a discrete molecular substance?

Answer 23

One that exists with separate molecules.

Question 24

What do most covalent substances exist as?

Answer 24

Discrete covalent molecules

Question 25

What type of bonding is found in a molecule?

Answer 25

Covalent

Question 26

Are covalent bonds inside molecules strong?

Answer 26

Yes, they are strong

Question 26

Are the bonds (forces of attraction) between molecules strong?

Answer 26

No, they are weak

Question 26

What term is used to describe bonds between molecules?

Answer 26

Intermolecular bonds/forces of attraction

Question 27

What does the formula of discrete covalent substances tell you?

Answer 27

The actual number of atoms in the molecule.

Question 27

Describe what is meant by a covalent network.

Answer 27

A giant structure where atoms are covalently bonded together.

Question 28

What information does the formula of a covalent network give you? e.g SiO2

Answer 28

Contains the simplest ratio of atoms of each element. e.g for every Si atom there are 2 0 atoms.

Question 29

Name 2 elements with a covalent network structure?

Answer 29

Silicon and Carbon (graphite and diamond)

Question 30

Name 2 compounds with a covalent network structure?

Answer 30

Silicon dioxide and Silicon carbide.

Question 31

What type of structure do ionic compounds have? (look at diagram for LI 37)

Answer 31

Ionic compounds consist of a lattice of oppositely charged positive and negative ions. An ionic crystal lattice.

Question 32

What information do you get from the formulae of an ionic compound? e.g MgCl2

Answer 32

The ratio of each ion present in the ionic crystal lattice.

Question 33

What is an electric current?

Answer 33

A flow of charged particles

Question 34

What charged particles can carry a current?

Answer 34

Freely moving/ Delocalised electrons OR ions.

Question 35

Why do metals and carbon (graphite) conduct electricity?

Answer 35

Metals and graphite both have delocalised electrons in their structure which are free to move.

Question 36

Why do covalent compounds not conduct electricity?

Answer 36

Covalent compounds consist of molecules that are uncharged, they contain no charged particles (either ions or delocalised electrons to carry a current.)

Question 37

In what state will ionic compounds conduct?

Answer 37

Ionic compounds don't conduct in the solid state but do when dissolved in water or when molten.

Question 38

Why do ionic compounds conduct when dissolved or molten but not when solid?

Answer 38

The ions are free to move when molten or dissolved but they are not free to move when solid as they are held in a lattice structure.

Question 39

Why do metals have high melting and boiling points?

Answer 39

the delocalised electrons are attracted to many surrounding positive ion cores.

Question 40

Why do ionic compounds have high melting and boiling points?

Answer 40

there is a strong electrostatic force of attraction between positive and negative ions.

Question 41

Why do covalent network structures have high melting and boiling points?

Answer 41

the mutual attraction of the shared pair of electrons to both positive nuclei.

Question 42

Why do discrete covalent molecular substances have low melting and boiling points?

Answer 42

Only weak force of attraction between molecules are broken when these substances melt/boil. The strong covalent bonds in the molecule are NOT broken.

Question 43

What can be said of the solubility of ionic substances in water?

Answer 43

They are usually soluble.

Question 44

Covalent substances may or may not soluble in water. What can those that are not be dissolved in?

Answer 44

Other covalent solvents such as hexane.

Question 45

What do metals and non-metals usually form?

Answer 45

ionic bonds

Question 46

How many non-metals usually form covalent bonds?

Answer 46

Two or more

Question 47

What is an element?

Answer 47

A substance that is made of only one type of atom. A chemical element is a chemical substance that cannot be broken down into other substances.

Question 48

What term is used to describe bonds between molecules?

Answer 48

"intermolecular forces are weak" Covalent bonds inside molecules are strong whereas the bonds (forces of attraction) between molecules are weak.

Question 49

What are some properties of ionic compounds?

Answer 49

High melting and Boiling Points, conduct in the liquid state ie dissolved in water, they do not conduct electricity in the solid state

Question 50

Name the shape of some 3 atom molecules (containing 2 bonds).

Answer 50

Angular/bent

Question 51

Name the shape of some 4 atom molecules (containing 3 bonds).

Answer 51

Pyramidal

Question 52

Name the shape of some 5 atom molecules (containing 4 bonds).

Answer 52

Tetrahedral