2.2 formulas and Key concepts

Question 1

What is the electron filling order?

Answer 1

1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p

Question 2

What is meant by the AUFBAU principle?

Answer 2

The idea that electrons enter the lowest available energy level

Question 3

What is meant by Pauli’s exclusion principle?

Answer 3

The idea that two electrons can go into an orbital providing that they are of opposite spin

Question 4

What is meant by Hund’s rule of maximum multiplicity?

Answer 4

The idea that when in orbitals of equal energy, electrons will try to remain UNPAIRED.

NOTE: They will later pair up when there is no more space

Question 5

How many electrons are in the 1st energy level?

Answer 5

2

Question 6

How many electrons are in the 2nd energy level?

Answer 6

8

Question 7

How many electrons are in the 3rd energy level?

Answer 7

18

Question 8

How many electrons are in the 4th energy level?

Answer 8

32

Question 9

What is meant by ionic bonding?

Answer 9

The electrostatic attraction between positively and negatively charged ions

Question 10

What is meant by covalent bonding?

Answer 10

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 11

What is the electron repulsion theory?

Answer 11

The idea that the shape adopted by a simple molecule or ion is that which keeps repulsive forces forces to a minimum

Question 12

Tips and Tricks for drawing 3D models

Answer 12

1) Draw the central atom
2) Find the number of electrons on the central atom’s outer shell
3) Add/Remove an electron for any charge the molecule has
4) Find out the number of bond pairs
5) Find out the number of lone pairs
6) Calculate the shape from the number of bond and lone pairs

Question 13

Why do diamond and graphite have a very different properties?

Answer 13

Diamond is a giant covalent structure made out of carbon bonds covalently bonded to other carbon bonds. Covalent bonding is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms. Diamond has a lot of strong covalent bonds holding the giant covalent structure together and so have high melting and boiling points. Diamond doesn’t conduct electricity as the electrons are “localised” (cannot move).

Graphite is made a covalent structure made out of carbon sheets. Unlike diamond, it is soft. This is because the sheets can easily slide past each other. Also, graphite has some delocalised (CAN move) electrons in between the sheets meaning that it is able to conduct electricity

Question 14

What is meant by electronegativity?

Answer 14

The ability of an atom to attract the bonding electrons in a covalent bond towards itself

Question 15

Under what circumstances is a compound be polar?

Answer 15

Where there is a difference (dipole) in electronegativity. E.g C-F

NOTE : An exception of this is carbon and hydrogen as similar atoms have similar electronegativity and so molecules will be non-polar

Question 16

What are the 3 types of intermolecular force?

Answer 16

Induced - dipole dipole interaction
Permanent dipole - dipole interaction
Hydrogen bonding

Question 17

How is an induced - dipole formed?

Answer 17

At any instant in time, it is possible that more electrons will lie to one side of the atom/molecules than the other
This creates an “instantaneous dipole” is produced
This induced a weak dipole in nearly atoms/molecules which creates weak forces between atoms/molecules

Question 18

How is an induced - dipole formed?

Answer 18

At any instant in time, it is possible that more electrons will lie to one side of the atom/molecules than the other
This creates an “instantaneous dipole” is produced
This induced a weak dipole in nearly atoms/molecules which creates weak forces between atoms/molecules

NOTE : This is the weakest type of intermolecular force

Question 19

How is a permanent dipole formed?

Answer 19

By differences in electronegativity

Polar molecules are held together with polar bonds
The extra attraction between dipoles means that MORE energy must be put in to the separate molecules

NOTE : It ONLY occurs between molecules containing polar bonds

Question 20

Describe hydrogen bonding

Answer 20

• All compounds that contain either nitrogen, oxygen and fluorine with hydrogen present in the compound will contain hydrogen bonds
• HOWEVER, just because a molecule has hydrogen in it, it DOESN’T mean it has a hydrogen bond in it (Exceptions being nitrogen,fluorine and oxygen)
• Hydrogen bonding is the strongest type of intermolecular force
• Hydrogen bonds are LONGER than other intermolecular forces
• Their strength and length explain water’s unusual properties

Question 21

Describe and explain 3 unusual properties of water

Answer 21

• Property 1 ( High surface tension and viscosity) - The strong H-bonds needs to be broken
• Property 2 (High melting/boiling point) - The strong and long H-bonds needs to be broken, which requires a lot more energy than the other 2 types of inter molecular forces
• Property 3 - (Ice floats on water) - The long H-bonds hold molecules apart in a lattice structure giving it a larger volume than liquid water