3.1 The Periodic Table (completed) Flashcards
3.1.1 Periodicity 3.1.2 Group II 3.1.3 Group VII
How is the periodic table arranged?
- Increasing atomic number
- Chemically similar elements
- Occur in the same groups
What is the trend for atomic radius across a period?
Decreases
Number of protons in nucleus increase so nuclear charge increases
The electrons are pulled in with a greater force shortening the atomic radius
What is the trend for first ionisation energy across a period?
Increases
The number of protons increase so there is more attraction acting on electrons
There is the same number of shells so same level of shielding but more nuclear charge
What is the trend for melting points across period three?
Na to Al: increases as there are more electrons in delocalised sea of electrons increasing force of attraction
Si: large increase due to giant molecular structure a lot of energy is required to break the bonds
P to Ar: much lower due to simple covalent molecules and weak intermolecular London forces the larger molecule the greater number of electrins and the stronger the London forces sulphur is larger as it exists as S8
What is the trend for first ionisation energy down a group?
Decreases
Number of shells increase so distance between nucleus and outer electrons decreases with a weaker attraction force and also more shielding electrons
What is group 2?
Alkali earth metals
What is the trend in reactivity down group two?
Increases
Electrons become easier to remove as the outer electrons are further from the inner attracting nucleus
More shielded from the attracting nucleus
Therefore if easier to remove it is easier to react
What is the reaction of group two metals with hydrochloric acid?
Acid + Metal → Salt + Hydrogen
What is the reaction of group two metals with oxygen?
Metal + Oxygen → Metal Oxide
What is the reaction of group two metals with water?
Metal + Water → Metal hydroxide + Hydrogen
How does the solubility of group two hydroxides change down the group?
Increases
More OH- in solution therefore the solution becomes more alkaline
What is the trend of thermal decomposition of group two carbonates?
All undergo thermal decomposition to give the corresponding white metal oxide and CO2
It becomes more difficult to decompose down the group
What is the reaction of group two oxides with water?
Metal oxide + Water → Metal hydroxide
What is calcium hydroxide used for?
It is used by farmers and gardeners to neutralise acid soils
What is magnesium hydroxide used for?
Milk of magnesia
It’s used to relieve indigestion by neutralising excess acid in the stomach