5th yr xmas Flashcards
Ground state
Low energy state for atom. Electrons are in the lowest available energy levels
Energy level
A shell containing electrons of equal energy
Excited state
High energy state for atom. Temporary and unstable state. Electrons have jumped to higher energy level having absorbed a fixed amount of energy
Atomic orbital
A region in space around the nucleus of an atom where there is a high probability of finding an electron
Sublevel
Found within energy level. Contains a group of atomic orbitals with similar energy
Heisenberg uncertainty principle
Not possible to know the exact position and velocity of electron at the same time
Atomic number
Number which gives the number of positive protons in the nucleus of an atom
Mass number
Total no of protons and neutrons in nucleus
Pauli’s exclusion principle
Only 2 electrons can occupy an atomic orbital and these must have opposite spin
Aufbau principle
Electrons must fill the lowest available energy sublevels first
1st ionisation energy
The energy required to remove the most loosely bound electron from 1 mole of neutral gaseous atoms in the ground state
Factors which influence I.E. values
*Size of positive nuclear charge. * size of atomic radius. * screening effect of inner shells. * stability of atom’s configuration
Decrease in I.E.
Configuration stability
Increase in I.E.
Atomic radius decreases. Positive nuclear charge increases. No increase in sceening effect
Define elctronegativity
The relative attraction an atom has for a shared pair of electrons in a covalent bond
Why do EN values vary going across a period of elements
EN values increase. Atomic radius decreases. Effective positive nuclear charge increases.
Why do EN valuse decrease going down a group
Atomic radius increases. The increasing positive nuclear charge is not effective as there is an increase in screening by shells of electrons
Intramolecular force. Inter
Force within a molecule. Between molecules
Hydrogen bond
The attraction between a slightly positive hydrogen in one molecule and a slightly negative N, O, or F in another adjacent molecule
Unusual properties in water and caused by what. What are these properties
Ice is less dense than liquid water. High surface tension Explains why water is a liquid at room temperature
Why is water an excellent solvent
Water molecules are polar (atoms carry sloght charges). Water will dissolve polar solutes - like dissolves like
One lone pair in a molecule - shape?
Pyramidal
2 bond pairs in molecule -shape?
V shaped
