periodic table and energy Flashcards
what is the definition of first ionisation energy
energy needed to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous +1 ions
what are the factors affecting ionisation energies
nuclear charge
distance from nucleus
shielding
explain how nuclear charge effects ionisation energies
higher positive charge means stronger attraction so higher energy
explain how distance from nucleus effects ionisation energies
attractions decreases rapidly with increased distance from nucleus so lower energy
explain how shielding effects ionisation energies
as number of electrons between the outer electrons and nucleus increases, the less attraction the outer shell electrons feel so lower energy
what is the definition of second ionisation energies
energy required to remove 1 mole of electrons from one mole of gaseous +1 ions to form 1 mole of gaseous +2 ions
How can orbitals effect ionisation energy
For example a 3p orbital has higher energy level than 3s so an element with its outer elections in a 3p orbital would have lower ionisation energy than one with outer electrons in 3s, as they are further away from nucleus
How does electronegativity change across period 3 and why
Across the period there are more protons so smaller atoms, this means there’s a greater attraction of two elections in a covalent bond to nucleus so increases
What is the periodic trend in mp and bp
Mp increases from group 1 to 4:
Groups 1 to 3 have metallic bonding
Which increases mp by increased attraction betwee n sea or elections and smaller positive ion (higher charge)
Group 4 has giant covalent structure with many strong covalent bonds
Sharp decrease from group 4 to 5:
Simple molecular with weak London forces
What is the oxidation rule about elements on their own
Always have oxidation state of zero
The what are the oxidation rules regarding groups
Group 1 is almost always +1
Group 2 is almost always +2
Group 7 is usually -1
What are the oxidation rules for oxygen
Usually -2 except in a peroxide
+2 when bonded to fluorine
What is the oxidation state rule for hydrogen
+1 except in a metal hydroxide
what are the factors of group 2
good reducing agents (they are oxidised)- stronger down the group
form oxides when reacted with oxygen (redox)
reacts with water to form a metal hydroxide and hydrogen
reactions are more vigorous down the group
more reactive down the group
reacts with dilute acids
why does reactivity increase down group 2
atomic radius increases so increased shielding, weaker attraction between positive nucleus and outer shell electrons
how and why does solubility of group 2 hydroxides, formed from a group 2 oxide and water, change down the group
become more soluble as there is a greater availability of OH- ions (pH increases down group)
explain how group 2 bases are used
agriculture- Ca(OH)2 sometimes added to fields to raise pH if needed
medicine- Indigestion remedies used to neutralise excess stomach acid CaCO
removal of SO2- CaO and CaCO3 is sprayed into flue gasses to neutralise it
how does solubility of group 2 sulfates change down the group
decreases
how and why does boiling point change down group 7
increases as there are more electrons so more london forces so more energy is needed to break them
what is the appearance of F2
pale yellow gas
what is the appearance of Cl2
pale green gas
what is the appearance of Br2
red/brown liquid
what is the appearance of I2
grey solid
what colour do bromine and iodine give when dissolved in water
orange/brown
