Chapter 7 Flashcards
How is the periodic table aranged?
Elements are arranged in terms of increasing atomic number
What are groups?
The elements which are in the same vertical column. They have the same number of electrons in the otuershelll and have similar properties
What are periods?
Elements whcih are arranged in horzintoal rows. The number of the period gives the number highest energy electron shell in an element’s atoms
What is periodicity?
Repeating trend in properties of the elements across a period.
Trend across period (shells)
S shells are filled up first with electrons follwoed by p subshells with 6 electrons
What is ionisation energy?
Energy required to remove 1-n electrons from each atom in one mole of gasesous atoms/n+ions
Factors which affect ionisaton energy
Atomic radious-the greater the distance bewteen the nucleus and the outer electrons, the less the nuclear attraction. Forces of attraction falls of sharply with increasing distance
Nuclear charge-the more protons there are in the nucleus, the greater the attraction between nucleus and outer electrons
Electron shielding-electrons are negatively charged and so inner-shell electrons repel outer-shell electrons. This is the shielding effect and reduces the attraction between the nucleus and outershell electrons
Sucessive ionisation energy
More energy is required to remove the next electron as nuclear attraction on the remaining electrons increases.
Trend in ionisation energy down a group
Ionsiation energy decreases down a group.
This is due to these factors:
Atomic radius increases
Shielding increases due to more inner electrons
Nuclear attraction on outer electrons decreases
Trend in ionisation energy across a period
It generally increases due to these reasons:
Nuclear charge increases
Nuclear attraction increases
Atomic radius decreases
Why does the first ionisation energy decrease from Beryllium to Boron?
The 2p sub-shell in boron has a higher energy than the 2s subshell in Beryllium. This means it is easier to remove a 2p electron than one of the 2s electrons in Beryllium.
Why does the first ionisation energy decrease from nitrogen to oxygen?
In oxygen, paired electrons in one of the p orbitals repel eachoter, making it easier to remove an electron from an oxygen atom than a nitrogen atom
Properties of metals
All metals are solid except mercury
Can conduct electricity
Strong metalic bonds
High melting and boiling pointsNot soulble
What is metalic bonding?
Electrostatic attraction between delocalised electrons and nucleus. Billions of metal atoms are held together by metalic bonding in a giant metalic lattice.
What are giant covalent structures?
Billions of atoms are held together by a network of strong covalent bonds to form a giant covalent lattice. Examples are Boron, carbon and silicon.
