Covalent Bonding (page 115)

Question 1

What is Covalent Bonds?

Answer 1

this is where atoms share electrons with each other so that they’ve got full outer shells.

Question 2

When Non-metal atoms bond together what happens?

Answer 2

they share pairs of electrons to make covalent bonds

Question 3

How are covalent bonds very strong?

Answer 3

the positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces, this makes covalent bonds very strong

Question 4

where do Atoms only share electrons?

Answer 4

in their outer shells (highest energy levels)

Question 5

Each single covalent bond provides how many extra shared electrons - - for each atom?

Answer 5

ONE extra shared electron

Question 6

Each atom involved generally makes enough covalent bonds to fill up its outer shell, what do this mean?

Answer 6

having a full outer shell gives them the electronic structure of a noble gas, which is very stable.

Question 7

Covalent bonding happens in compounds of metals or non-metals?

Answer 7

Non-metals (e.g. H20) and in non-metal elements (e.g. Cl2)

Question 8

There are different ways of drawing covalent bonds, what are the diagrams you can use?

Answer 8

1) dot and cross diagram
2) the displayed formula
3) 3D model

see diagrams on page 115 in book)

Question 9

What is the dot and cross diagram used for?

Answer 9

it is used to show the bonding in covalent compounds

Electrons are drawn in the overlap between the outer orbitals of two atoms, they are shared between those atoms.

Dot and cross diagrams are useful for showing which atoms the electrons in a covalent bond come from, but they don’t show the relative sizes of the atoms, or how the atoms are arranged in space

(the importance of drawing these diagrams are to make sure you get all the dots and crosses in the right places - see diagram on page 115 in book)

Question 10

What is the Displayed Formular diagram used for?

Answer 10

the displayed formlar diagram shows the covalent bonds as SINGLE LINES between atoms.

this is a great way of showing how atoms are connected in large molecules. However, they don’t show the 3D structure of the molecule, or which atoms the electrons in the covalent bond have come from.

eg; H
|
H - N - H

(the lines inbetween is the covalent bond)

this displayed formula is of ammonia (NH3)

Question 11

What is the 3D model for convalent bonding used for?

Answer 11

the model show the atoms, the covalent bonds and their arrangement in space next to each other.

The 3D models can quickly get confusing for large molecules where there are lots of atoms to include.

They don’t show where the electrons in the bonds have come from either.

Question 12

How can you find the molecular formula of a simple molecular compound using a diagram? (dot and cross/displayed formular/3D)

Answer 12

you can find a simple molecular compound from any of these diagrams by counting up how many atoms of each element there are

Question 13

What is the Molecular formlar of ethane?

               H        H
                |         |
        H - C    -   C - H
               |          |
              H         H

Answer 13

The diagram shows two carbon atoms and six hydrogen atoms, so the molecular formular is C2H6

Question 14

Practice drawing the diagrams for

Dot and Cross
Diaplayed Formular
3D model

these will be in your exam

Answer 14

practice from examples on page 115 in book

Question 15

Draw a dot and cross diagram to show the bonding in a molecule of ammonia (NH3) (2 marks)

Answer 15

Answer is at the back of answer book (page 244, question 115)