02 - electrons in atoms Flashcards
what is electronic configuration?
- way of represting electronic arrangement in an atom showing: (1) principle quantum shell (2) sub-shells (3) number of electrons present
- shell 1 = 2 electrons
- shell 2 = 8 electrons
- shell 3 = 18 electrons
-shell 4 = 32 electrons
what is first ionisation energy?
- energy required to remove 1 mole of electrons from 1 mole of atoms of an element in the gaseous state to form 1 mole of gaseous 1+ ions
- symbol = IE1
- kJ mol-1
- in equation WRITE (G) STATE SYMBOL
what are successive ionisation energies?
- energy requires in each step to remove the first, then second, then third electron from a gaseous atomuntil only the nucleus is left
- increase for each element (net positive charge increases, so more attraction, so more energy needed)
- big changes = 2nd is in a different shell closer to the nucleus
factors that influence ionisation energy?
-NUCLEAR CHARGE inceases, IE increases (atomic number increases, positive nuclear charge increases, so bigger attractive force between nucleus and electrons, so more energy needed to overcome)
-DISTANCE BETWEEN OUTER ELECTRON AND NUCLEUS increases, IE decreases (distance increases, force of attraction decreases, less energy required)
- SHEILDING EFFECT OF INNER ELECTRONS/ no. of full electron shells between increases, IE decreases
-SPIN PAIR REPLUSION (electron in same orbital repel each other more than in different, more repulsion=easy to remove electron)
what is shielding?
the ability of inner shell electrons to reduce the effect of nuclear charge on outer electrons
what is the order of subshells in increasing energies?
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d
what are atomic orbitals?
- regions of space outside the nucleus that can be occupied by a maximum of two electrons
- named s, p, d, f
- have different shapes
s = 1 orbitals (circle shape)
p = 3 orbitals (infinity on axis)
d = 5 orbitals (modified p with ring around middle)
what are sub-shells?
- regions of the principle quantum shells where elctrons exsit in defined areas as so with particular amounts of energy
- named s, p, d, f
- order of filling (increasing energy): 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d
representing electronic configurations:
1s²
principal quantum number, subshell, no of electrons
EXCEPTIONS: (more energetically stable)
- chromium: 3d^5 4s¹
- copper: 3d^10 4s¹
orbitals and the periodic table?
- s block: groups 1, 2
- p block: groups 13 to 18
- d block: mostly transition elements
drawing orbitals?
- each box is one atomic orbital
- in order of increasing energy (bottom to top)
- electron represented by an arrow
- arrow direction = electron spin
- 2 electrons max in one orbital
- 2 electrons spin in opposite directions
what is spin-pair repulsion?
- an electron pair in the same orbital repel each other (same charge)
- spinning them in opposite directions reduces repulsion
- more repulsion in lone electrons than pairs
- electrons prefer to be alone than paired, only paired when no more empty orbitals
what is a free radical?
- species with one (or more) unpaired electrons
- shown with a dot
what is atomic radius?
- half the distance between the nuclei of two covalently bonded atoms of the same type
- increases down any group (more electron shells, also more nuclear charge BUT reduced by shielding)
- decreases across any period
(more protons, new electron only in same shell, more acctractive force, outer shell pulled closer to nucleus) - IONIC RADIUS: same trend for same reasons
IE1 patterns across a period?
- GENERAL INCREASE IN IE1: nuclear charge increases, distance is constant, shielding is constant
- RAPID DECREASE IN IE1 BETWEEN LAST AND FIRST ELEMENTS IN DIFFERENT PERIODS: distance increases, shielding increases, outweight nuclear charge
- IE1 DECREASE BETWEEN Be (2s²) and B (2s² 2p¹): distance increases, shielding increases, outweigh nuclear charge
- IE1 DECREASE BETWEEN N and O: N electron is unpaired so no repulsion to reduce energy
