Atomic Structure Flashcards
Subshell
A specific energy level within an electron shell. Designated s, p, d or f in order of increasing energy
Order of subshells in increasing energy
s, p, d, f
Orbital
A region of space in which up to two electrons may be located
How many orbitals in a p subshell?
3
How many electrons can fit in a d subshell?
10
How many orbitals in an s subshell?
1
How many electrons would be in an f subshell if all the orbitals were half-filled?
7
Order of subshell filling up to 6p
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p
Pauli Exclusion Principle
A maximum of two electrons can fit into any orbital, providing that those electrons have opposite spin
Hunds Rule
Electrons will arrange themselves into a subshell in such a way as to maximise the number of half-filled orbitals. OR Electrons will half-fill all orbitals in a subshell before any are filled completely.
Aufbau principle
Electrons will move into subshells in order from lowest energy up to highest energy
Ground state
A situation where all electrons in an atom or ion are in the lowest possible energy levels (subshells)
Excited state
A situation where not all electrons in an atom or ion are in the lowest possible energy levels (subshells)
Which two elements in the first row of the d block have only one 4s electron?
Chromium and Copper
What causes a spectral line on an emission spectrum?
An excited electron relapsing into a lower energy subshell
What shape is an s orbital?
Sphere
How many electrons can fit into the 3rd shell, and how many of these electrons fit into each subshell?
A total of 18 - 2 in the s subshell, 6 in the p subshell and 10 in the d subshell
What is meant by the term ‘isotopes’?
Two atoms that have the same number of protons (atomic number) but a different number of neutrons (or different mass number)
From which subshell would an iron atom lose its first electron?
The 4s subshell
Trend in atomic radius across a period (L to R), and why
Atomic radius decreases because core charge increases but the number of shells remains the same
Trend in atomic radius down a group, and why
Atomic radius increases because the number of shells increases but core charge remains the same
Trend in core charge across a period (L to R), and why
Core charge increases because the atomic number increases but the number of inner shell electrons remains the same
Trend in core charge down a group, and why
Core charge remains the same because the atomic number and the number of inner shell electrons increase by the same amount
How to calculate core charge
Number of protons in the nucleus minus the number of inner shell electrons
Core charge of a Silicon atom
4+ (14 protons minus 10 inner shell electrons)
Core charge of a Magnesium 2+ ion
10+ (12 protons minus 2 inner shell electrons)
Core charge of a Sulfide ion
6+ (16 protons minus 10 inner shell electrons)
Trend in electronegativity across a period (L to R), and why
Electronegativity increases because core charge increases and atomic radius decreases slightly (note that noble gases are an exception as they do not easily participate in bonding)
Trend in electronegativity down a group, and why
Electronegativity decreases because atomic radius increases (due to increasing number of electron shells) but core charge remains constant
Definition of ‘first ionisation energy’
The amount of energy required to remove an electron from each of a mole of gaseous atoms (of that element) to produce a mole of 1+ ions
Trend in first ionisation energy across a period (L to R) and why
First Ionisation Energy increases due to increasing core charge and slight decrease in atomic radius
Trend in first ionisation energy down a group and why
First Ionisation Energy decreases due to increasing atomic radius (due to increasing number of electron shells) but core charge remains constant
Define Electronegativity
The force of attraction experienced by bonding electrons towards the nucleus of that element
Which group has the highest electronegativity in any period after the first?
Group 7 (the halogens)
Which group has the lowest electronegativity in any period after the first?
Group 1 (the alkali metals)
Which group has the highest first ionisation energy in any period after the first?
Group 8/0 (the noble gases)
Which group has the lowest first ionisation energy in any period after the first?
Group 1 (the alkali metals)
How can you work out the group number of an element using successive ionisation energies?
The number of electrons removed before the first big ‘jump’ in ionisation energies is the number of valence electrons (and therefore group number)
Why is the third ionisation energy of calcium much greater than the second?
The third electron is removed from a lower-energy shell than the first two. This electron will be closer to the nucleus and experience much less electron shielding.
What is electron shielding?
A repulsive force exerted by electrons that are closer to the nucleus (ie in lower energy shells) on electrons that are further from the nucleus (ie in higher-energy shells), pushing them away from the nucleus
Trend in the reactivity of metals down groups 1 and 2, and why
Reactivity increases because electrons are lost more easily, because the atomic radius increases but core charge remains the same
What is common about metals that are found in the native state?
They are very unreactive. Examples include gold, silver and platinum.
Trend in the reactivity of non-metals down group 7, and why
Reactivity decreases because it becomes harder for the halogen to attract an electron due to increasing atomic radius (more electron shielding) while core charge remains the same
Definition of relative isotopic mass
Mass of that isotope relative to 1/12 the mass of a carbon-12 isotope
Definition of relative atomic mass
The weighted average mass of all the isotopes of that element, weighted by their relative abundance
Formula to calculate moles from mass and molar mass
n = m/Mr
Formula to calculate moles from concentration and volume of a solution
n = CV
Formula to calculate moles from volume and molar volume of a gas (at SLC)
n = V/Vm (or V/24.8)
Formula to calculate number of particles (N) from moles and Avogadro’s number (6.02 x 10^23)
N = n x 6.02 x 10^23
How many moles of hydrogen atoms are present in 2.5 moles of water?
5 moles of hydrogen atoms
How many moles of atoms are present in 2.5 moles of water?
7.5 moles of atoms (2.5 moles of oxygen atoms plus 5 moles of hydrogen atoms)
