Periodocity Flashcards
Define relative nuclear charge
+ charge from protons in nuclear of atom
Define shielding
How many completed shells are between the outermost electrons and the nucleus
What is shielding
Mr Walter 4 marker but add in that the inner shells shield the outermost electron from further attraction
How does the distance from the nuclear change going down the group
Increases as more shells occupied so outer electron is further away from the Nucleus the attraction < but atomic radius>
How does the distance from the nuclear change going across a period
Decreases slightly as the proton no. increases as electrons are added to the same sheet so the attraction and atomic radius both increase
Define first ionisation energy
Na(g) –> na+(g) + e-
Define first electron affinity
S(g) + e- —-> s-
How does electronegative affect the trend across a period
Nuclear charge increases so does the attraction between shared pair of electrons in covalent bond
How does electronegative affect the trend down the group
Although the nuclear charge is increasing, the effective nuclear charge is less due to the shielding of inner shells and distance from outer electron
How does the first ionisation energy effect the trend across a period
Increases cause stronger positive charge due tk an increase in relative charge
Define exothermic reaction
Release thermal energy into surroundings
Define endothermic reactions
Take in thermal energy from surroundings
Ionisation energy and reactions
Looses electrons so always endo
Electronic affinities and reactions
Gains electrons
1st is ex
Rest are endo as negative electron is out onto another negative ion having to overcome repulsion
Define mp
Measure of energy required tk separate particles in a substance (intermolecular forces)
