5 - Electrons and bonding

Question 1

shells

Answer 1

• energy levels
• energy increases as shell number increases
• shell number/energy level is called the principle quantum number n

Question 2

what are shells made up of

Answer 2

atomic orbitals

Question 3

what are atomic orbitals

Answer 3

a region around the nucleus that can hold up to two electrons with opposite spin

• there is a high probability of finding an electron

Question 4

how can electron be thought of

Answer 4

a negative-charge cloud with the shape of the orbital

Question 5

what is an orbital

Answer 5

• Orbital is a region around the nucleus that
  can hold up to two electrons, with opposite
  spins
• there are types s,p,d,f
• each type has a different shape

Question 6

s-orbital

Answer 6

electron cloud in the shape of a sphere

can hold up to 2 e-

each shell from n=1 has one s-orbital

the greater the shell number the greater the radius of its s-orbital

Question 7

p-orbitals

Answer 7

electron cloud is in the shape of a dumb-bell

one p-orbitals can have 2 e-

there are 3 orbatals at right angles in the x,y,z plane

each shell from n=2 has 3 p-orbitals

the greater the shell number the further the p-orbital is from the nucleus

Question 8

d-orbitals

Answer 8

each shell from n=3 has five d-orbitals

Question 9

f orbitals

Answer 9

each shell from n=4 has 7 f-orbitals

Question 10

sub-shells

Answer 10

within shells orbitals of the same group are called sub-shells

Question 11

filling of the sub-shells

Answer 11

the 3d sub shell is are a higher energy level than the 4s sub shell so the 4s sub shell fills before the 3 d sub shell

therefore the order of filling is
3p 4s 3d

Question 12

ionic bonding

Answer 12

electrostatic attraction between positive and negative ions

Question 13

structure of ionic compounds

Answer 13

giant ionic lattice

Question 14

physical properties of ionic compounds and why

Answer 14

Tm + Tb
- mostly solid at RTP
- as there is insufficient energy to overcome the strong electrostatic forces of attraction between the oppositely charged ions in the giant ionic lattice
- melting points are higher in lattices containing ions with greater ionic charges as there is a stronger electrostatic force of attraction

solubility
- ionic compounds dissolve in polar solvents like water, water ions surround each ion and break down the lattice
- in ionic compounds with larger charges, the ionic attraction could be too strong and might not be soluble

conducts
- In the solid state, the ions cannot move as
they are fixed in a giant ionic lattice structure
In solution, ions are free to move and carry
charge

Question 15

covalent bonding

Answer 15

A covalent bond is the strong electrostatic
attraction between a shared pair of electrons
and the nuclei of the bonded atoms

• it is the overlap of atomic orbitals

Question 16

why is a covalent bond localised

Answer 16

attraction is localised acting only between the shared pair of electrons and the nuclei

Question 17

dative/coordinate bond

Answer 17

A dative covalent bond is a shared pair of
electrons where both electrons are from the
same atom