Pure Memory AS Module 2

Question 1

Why do isotopes have the same chemical propertied? (2)

Answer 1

Isotopes of an element have the same number of protons and electrons but different number of neutrons, and are the same element

The chemical properties are determined by the electronic structure / electrons in the OUTER shell only, thus isotopes have the same chemical properties

Question 2

Isoptopes definition

Answer 2

Same number of protons/ electrons, but different mass number due to having different number of neutrons

Question 3

Relative isotopic mass?

Answer 3

Mass of an isotope relative to 1/12th the mass of an atom of CARBIN 12

Question 4

Relative atomic mass (2)

Answer 4

WEIGHTED MEAN MASS OF AN ATOM OF AN ELEMENT
- relative to 1/12th the mass of an atom of carbon 12

Question 5

What is water of crystallisation?

Answer 5

Many salts exist HYDRATED, so water molecules exist as part of their structure

When this is heated away, you get ANHYDROUS

Question 6

2 assumptions made when doing water of crystallisation PAG

Answer 6

1) that all the water has been heated off
- can do this by getting consistent readings to constant mass

2) that no FURTHER DECOMPOSITION OF THE SALT HAS TAKEN PLACE, and thus less mass…

Question 7

Base , salt , alkali definition

Answer 7

Base is a substance that can neutralise an acid

Salt is an acid whose h atoms replaced by metal

Alklai is a soluble base and dissociates to form OH - ions

Question 8

Redox SPECIAL CASES?
H metal hydride
O in peroxides
O bonded to F

Answer 8

H = -1
O= -1
O = +2

Question 9

Atomic orbital

Answer 9

A region around the nucleus that can hold up to two electrons of opposite spin

Question 10

How is electrons organised
Shell
Sub shell
Specific orbitals

Answer 10

Each shell has quantum number
N =1 had one s sub shell. This has 1 s orbital
N=2 has 1 s sub shell and a p sub shell, s sub shell has 1 orbital and p has 3. P orbitals agsin 2 electrons
Etc

Question 11

S sub shell and sub shell shape

Answer 11

S is sober, p is dumbbell

Question 12

Periodic split into s , d , p blocks?

Answer 12

Based on the highest energy sub shell the electron configuration shows

Question 13

Electorn pair repulsion theory 3 points

Answer 13

1 electron pairs around the central atom repel each other as far apart as possible
2) has this many pairs and lone pairs.3) lone pairs repel more than bonded pairs

Therefore

Question 14

Sulfur dioxide specific shapes ( 2 double binds one lone pair )

Shape and angle?

Anomaly

Answer 14

Non linear shape but 120° angle

• because the double bonds have similar repulsion as the lone pair
  So repulsion is even = 120°
• but non linear shape just learn this one?

Question 15

Electronegativity definition

Answer 15

The ability of an atom to attract the pair of electrons in a covalent bond

Question 16

Why does electronegativity increase more right and up the periodic table you go

Hence which is most electro atoms

Answer 16

The ability to attract the electron pair comes from the nuclear charge . Going right the periodic table, the nuckear charge increases, but the nuclear radius also decreases, which increases nuclear attraction
- going down period increases charge but radius bigger (and shielding) so nuclear attraction defreasss

Therefore F O N most electronegative

Question 17

How do induced dipole dipole interactions come about

3 points

Answer 17

1) movement of electrons in a molecule means at any instant, an INSTANTANEOUS DIPOLE WILL EXIST , but it’s position constantly changing
2) this INSTANEOUS dipole will induce a dipole on a neighbouring molecule, which will induce a dipole on its neighbour etc
3) the ATTRACTION between induced dipoles is called an induced dipole dipole interaction

A

Question 18

How does number of electrons increase the London firce strength

And thus boilign pint

Answer 18

1) the larger the number of electrons in a molecule
2) the larger the INSTANEOUS dipole and thus induced dipole
3) so the stringer the attraction between induced dipoles/ stringer the induced dipole dipole interaction

Thus more energy needed to overcome these interactions and boiling point increases

Question 19

Does everything have London forced

What doesn’t

Answer 19

GIANT COVALENT DOESNT

So like SIO2, watch out for group 4 to chekc

Question 20

Solubility for simple molecular structure

Polar non polar mixes

Answer 20

Non polar and non polar (energy made enough )
Polar and polar is similar to polar and ionic, the polar substance attracts the polar molecular structure etc

Polar non polar no

Question 21

Anomalous properties of water

2 main ones

Answer 21

1) higher density as a liquid then solid
- when becoming a liquid, hydrogen bonds in the water hold water molecule apart in an OPEN LATTICE structure .
( this is further average distance apart than when liquid, so same mass for more volume means less density )
- therefor ice floats

2) higher melting and boiling points
- (boiling pint ) because if hydrogen bonds mean more energy is needed to overcome then without would be just London

Question 22

Remember structure for simole molecular why does it have low boiling

Answer 22

As the ATOMS are covalently bonded, but the molecules are attracted by weak London forced

These are the ones that are overcome, not much energy needed thus low boiling points