Topic 1 Atomic Structure & Periodic Table Flashcards
What is a mass number?
number of protons and neutrons in the nucleus of an atom
What is a relative isotopic mass? (2 marks)
the mass of an atom of the isotope compared to 1/12th of Carbon-12 (1)
which has mass of 12
What is a relative atomic mass? (Ar)
the weighted mean mass of all isotopes of an element relative to 1/12 of the mass of an atom of carbon-12
What is a Relative Molecular Mass? (Mr)
Aka relative Formula mass (esp when it is an ionic compound)
the sum of Ar present in a molecule
What is an orbital?
A region within an atom that can hold up to two electrons with opposite spins.
Define isotopes (2 marks)
The element with same number of protons but different numbers of neutrons
Definition of first IE (2 marks)
energy needed to remove 1 mole of electrons from a gaseous atom
X (g) -> X+ (g) + e-
Definition of second IE
Energy required to remove 1 mole of electrons from 1 mole of 1+ gaseous ions to form 1 mole of 2+ gaseous ions under standard conditions
What is a successive IE
the energy that is required to remove the electron one after the other
3 factors affecting IE
- nuclear charge (num of protons)
- attraction
- shielding
(- atomic radius that decreases down a period)
What is periodicity?
Pattern/trend of physical/chemical properties repeated across a period
What are the 5 stages off mass spectrometry?
Vapourisation
Ionisation
Acceleration
Deflection
Detection (1+ charge as E- knocked off)
VIADD
The bigger the ion… (in terms of mass spectrometry)
The less the deflection
Only what are detected in mass spectrometry?
Ions (1+ charge)
Why is mass spectrometry taken place in a vacuum?
So don’t slow molecules down from deflections
And prevent collisions with air particles
What does mass spectrometry tell you?
- fragments of ions in a molecules
What does infrared tell you?
- functional groups
- dnf
Define periodicity
In terms of atomic radii of period 2 and 3 elements.
It is the repeated physical and chemical properties across a period (with increasing atomic number)
Atom radii decreases from left to right due to increased attraction between nucleus and e-s
Also repeated in Period 3
what are isotopes?
atoms of the same element with same num of protons but diff num of neutrons
State and explain the trend in first IE down periodic table groups (except G3). 2 marks
Decreases down
- increasing number and energy of subshells
- increasing atomic radius and sheilding
- so lose outer e easier
why is first IE of Boron less than Beryllium, even though Boron has higher nuclear charge?
Be - 1s2 2s2
B - 1s2 2s2 2p1
B’s outer e has higher energy in a higher energy orbital
but there is more electron-electron repulsion in the 2s2 orbital (Be) as opposed to 1 in 2p1 (B)
what is periodicity?
repeating patterns across a period of the periodic table
what is the first IE trend across Period 3? (3 marks)
- due to increasing nuclear charge
- e-s added to the same quantum shells so increase of shielding is minimal
- energy of outer e-s decrease (outweighed by increasing nuclear charge)
[i dont rlly like this Q]
what is the trend in atomic radii across period 3? (3 marks)
decreasing atomic radii
since nuclear charge is increasing
increasing attractive force of electron-electron repulsion, num of outer quantum shell increases
