TOPIC 1 - ATOMIC STRUC AND PERIODIC TABLE

Question 1

Ionic equations

Answer 1

. only show show substances that are involved in the reaction basically formation of ionic compounds from ions(aq).
. First split main eq into ions composed of and identify the ionic compound formed and write ionic eq. The rest is spectator ions (do not change and not involved in reaction.)

Question 2

Describe struc of atom

Answer 2

. made of subatomic particles - protons and neutrons in the nucleus and electrons in the electronic shells surrounding the nucleus.
. protons relative mass = 1 and charge +1
. neutron r.m = 1 and charge = 0
. electrons r.m= 1/1840 and charge = -1 .
Same e- config= same chemical reactions/ properties

1800’s John Dalton’s atomic theory:
- all atoms of an element are identical and atoms can not be divided.
JJ Thompsons’s theory:
- Atoms contain electrons and overall charge of an atom is neutral due to Plum pudding model _ e- scattered throughout + charge
Ernest Rutherford Nuclear model - gold foil experiment
charged + alpha particles at gold foil some deflected back shows + charge of atom and most of its mass is concentrated in nucleus at center and e- orbit around. Most of atoms volume is the space. Proved balance of charge.
Niels Bohr Planetary Model
Orbiting e- attracted to opposite charged nucleus and occupy in fixed energy levels.
James Chadwick - Neutrons

Question 3

Atomic number

Answer 3

Number of protons in the nucleus of an atom of that element = no. of e-

Question 4

Mass number

Answer 4

Sum of the protons and number of neutrons in the nucleus of that atom

Question 5

Isotopes

Answer 5

Atoms of the same element with the same amount of protons and electrons but different amount of neutrons

Question 6

Relative atomic mass

Answer 6

The weighted mean mass of an atom of an element compared to 1/12 the mass of an atom of carbon-12

Calc by %abundance times by relative mass of isotope and add all isotopes divide by 100.
Make sure all abundance adds up to 100

Question 7

Relative isotopic mass

Answer 7

The mass of an isotope compared to 1/12th of the mass of an atom of the isotope Carbon-12

Question 8

mass spectrometer measure?

Answer 8

mass of molecules and compounds and relative abundances of diff. isotopes and predict struc of more complex molecules.

Question 9

Molecular ion peak (M+)

Answer 9

Peak with the HIGHEST m/z ratio in the mass spectrum. Determines an exact Relative Molecular Mass. The strongest peak furthest to the right

Question 10

When should the term ‘Relative Formula Mass’ be used?

Answer 10

For compounds with giant structures

Calc by the elements Mr times by no of atoms and add all together

Question 11

Why do we use empirical formula for giant struc and not molecular formula

Answer 11

coz struc is infinitive and there are number atoms of an element - too many to count.

Question 12

In a Mass Spectrum of an element, what does the number of peaks show?

Answer 12

The number of isotopes

Question 13

4 processes in a mass spectrometer

Answer 13

Ionisation - vaporizes sample and high volt applied/high energy e- and e= lost and ion formations.
Acceleration - + ions accelerated by electric field in uniform speed and smaller ions ( low m/z) have a greater speed than larger ones
Deflection - In magnetic field the lighter they are, the more they are deflected. greater charge more deflected, shorter time to hit detector.
Detection - ions create a current and time taken is recorded. Greater abundance of isotopes = larger current. Greater no. particles landing at a single point, greater e- current and larger the peak.
The amount of deflection, therefore the mass of the atom.

Question 14

Why must a vacuum be used in a mass spectrometer?

Answer 14

• It means no interference from atoms or molecules in air

- Molecular fragments could not exist otherwise

Question 15

Orbital

Answer 15

a region within an atom that can hold up to two electrons with opposite spins

Question 16

Quantum shells

Answer 16

energy levels of an electron - lowest inside.

Question 17

Auf Bau Theory

Answer 17

e- always fll the lowest energy orbital first.

Question 18

Hund’s rule

Answer 18

electrons will occupy the orbits singly before pairing up

Question 19

Pauli’s EXCLUSION Principle

Answer 19

Two electrons cannot occupy the same orbital unless they have opposite spins (↑↓)

Question 20

Orbital shapes

Answer 20

s orbital - spherical hold 2e-
p orbital - dumbbell/hourglass shape, all axis/oreinatations smaller x,y,z energy level symbols. hold 6 e-
d hold 10e-.
4s goes FIRST then 3d as it has a lower energy than 3d.

Question 21

Periodicity

Answer 21

Regular repeating pattern of atomic, physical and chemical properties with increasing atomic number

Question 22

First Ionisation energy

Answer 22

Lost e- to the right
X(g)➝X+(g) + e-
The energy required to remove an electron from each atom in ONE MOLE of atoms in the GASEOUS state to form ONE MOLE of Gaseous 1+ IONS

Question 23

Second Ionisation Energy

Answer 23

X+(g)➝X2+(g) + e-
The energy required to remove an electron from each +1 charged positive ion in ONE MOLE of positive ions in the GASEOUS state

Question 24

3 Factors influence ionisation energies in an atom?

Answer 24

• proton number/ nuclear charge
• electron shielding
• electron orbitals (subshells)

DOWN THE GP - FRIST IE DECRESEASES
nuclear charge, e- shielding, atomic radius increases so nuclear attraction btw outershell e- DECREASES.

ACROSS THE PERIOD, IE INCREASES:
nuclear charge increases, atomic radius decreases as the e- shielding stays the same so the nuclear attraction on outershell e- INCREASES. THEREFORE MORE ENERGY IS NEEDED to remove it.

Question 25

Evidence for quantum shells

Answer 25

Successive ionisation energies.

Big jump after 2nd IE means easy to lose 2 electrons so the element is in group 2

Question 26

K vs Ar

Answer 26

K lower IE than Ar. As Ar very unreactive and stable e- config. In K, 1 unpaired e- and more e- shielding btw nucleus and outershell e- and larger atomic radius so less energy required to remove it .

Question 27

Anomalies across Period 3 in IE
Mg vs Al
P vs S

Answer 27

• Al lower IE than Mg due to less energy required to remove an e- from the p -orbital than s-orbital.
• S has lower IE as it is easier to remove an e- from a pair due to more electron repulsion.

first IE of gp 3 is LESS than gp 2
first IE of gp 6 is Less than gp 5

Be and B anomalies - B lower IE easier remove e- due to 2p orbital and has 2 complete s orbitals so increase shielding
N and O anomalies - O removed form pair

Question 28

melting and boiling temp across period 3

Answer 28

Metals loose e- so forces of attraction increases btw nucleus and shells so more energy required to break bonds so high mpt and bpt
Non- metals have weak forces of attraction and weak Van der Waals due to constant random movement of e- so london forces require less energy to break so low mpt and bpt

Question 29

First electron affinity

Answer 29

is the energy released when 1 mole of gaseous atoms acquire or gain an electron to form 1 mole of gaseous ions -1.

USE GAS STATE DYMBOLS

Question 30

strongest reducing agent is up the group of metals. so they cause others go oxidise easily so Li then Na

Question 31

Stongest oxidising agent at the top of group of non-metals is F. So more easily oxidised down the group