Module 3 – Periodic Table & Energy Flashcards
What is a common name given to group 2 metals?
Alkaline earth metals
What is the most reactive metal of group 2?
Barium
List 3 physical properties of group 2 metals
- High melting and boiling points 2. Low density metals 3. Form colourless (white) compounds
The highest energy electrons of group 2 metals are in which subshell?
S subshell
Does reactivity increase or decrease going down group 2? Why?
- Increases - Electrons are lost more easily because larger atomic radius and more shielding
What happens to the first ionisation energy as you go down group 2? Why?
Decreases because: - Number of filled electron shells increases down the group, therefore increased shielding - Increased atomic radius therefore weaker force between outer electrons and nucleus - So less energy needed to remove an electron
What type of reaction is the reaction between group 2 elements and oxygen?
Redox reaction
Write an equation for the reaction of calcium and oxygen
2Ca (s) + O2 (g) -> 2CaO (s)
What is the product when group 2 elements react with water?
Hydroxide and hydrogen gas
Which group 2 element doesnt react with water?
Beryllium
Which group 2 element reacts very slowly with water?
Magnesium
What type of reaction is the reaction between group 2 metals and water?
Redox reaction
Write an equation for the reaction of Barium and water
Ba (s) + 2H2O (l) -> Ba(OH)2 (aq) + H2 (g)
What is oxidised and what is reduced in a reaction between a group 2 metal and water?
The metal is oxidised One hydrogen atom from each water is reduced
What are the products when a group 2 element reacts with dilute acid?
Salt and hydrogen gas
Write an equation for the reaction of calcium and hydrochloric acid?
Ca (s) + 2HCl (aq) -> CaCl2 (s) + H2 (g)
What is formed when group 2 oxides react with water?
Metal hydroxide
Write an equation for the reaction between a group 2 oxide (M) and water
MO (s) + H2O (l) -> M(OH)2 (aq)
What group 2 metal oxide is insoluble in water?
Beryllium oxide
What is the trend in hydroxide solubility down group 2?
- Increases down the group - Mg(OH)2 is slightly soluble - Ba(OH)2 creates a strong alkaline solution
What is Ca(OH)2 used for? Write an equation related to one of its uses
Used to neutralise soil Ca(OH)2 (aq) + 2HCl (aq) -> 2H2O (l) + CaCl2 (aq)
What is Mg(OH)2 used for?
An antacid to treat indegestion, heartburn, ect
What is calcium carbonate used for?
Present in limestone and marble Used in building construction
What is the drawback of using calcium carbonate in construction? Write a related equation
Group 2 carbonates react with acid CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O (l) + CO2 (g)
How are the elements arranged in a periodic table?
They are arranged in the order of increasing atomic numbers
What is a period on the periodic table?
The horizontal rows in the periodic table
What is a group on a periodic table?
The vertical columns
What is meant by periodicity?
The repeating trends in chemical and physical properties
What change happens across each period?
Elements change from metals to non-metals
How can the electron configuration be written in short?
The nobel gas before the element is used to abbreviate
E.g. Li -> 1s22s1 ; Li -> [He] 2s1
Define first ionisation energy
The energy required to remove one electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions
Write an equation for the first ionisation energy of magnesium
Mg (g) -> Mg+ (g) + e-
What are the factors that affect ionisation energy?
Atomic radius
Nuclear charge
Electron shielding or screening
Explain the trend on this graph
First ionisation energy increases across period 3 because of: Increased nuclear charge
Decreased atomic radius
Same electron shielding
So more energy is needed to remove the first electron
Dips at Al because:
Outer electron is in a 3p orbital
3p orbital is higher energy than 3s orbital
Less energy is needed to remove the electron
Dips at S because:
One 3p orbital contains 2 electrons
Repulsion occurs between the paired electrons
Less energy is needed to remove an electron
Why does first ionisation energy decrease between group 2 and 3?
In group 3 the outermost electrons are in p orbitals
In group 2 the outermost electrons are in s orbitals
Electrons in p orbitals are easier to remove
Why does first ionisation energy decrease between group 5 to 6?
Group 5 electrons in p orbital are single electrons
Group 6 electrons are spin paired, with some repulsion
So group 6 electrons are easier to remove
Does first ionisation increase or decrease between the end of one period and the start of the next? Why?
Decrease
Atomic radius increases
Electron shielding increases
Does first ionisation increase or decrease down a group? Why?
Decrease
Shielding increases so attraction is weaker
Atomic radius increases
Distance between the outer electrons and nucleus increases
Attraction is weaker
Increase in number of protons is outweighed by increase in distance and shielding
What are the properties of giant metallic lattices? (4)
High melting and boiling point
Good electrical conductors
Malleability
Ductility
What is a ductile metal?
A metal which can be stretched
E.g. can be made into wires
What is a malleable metal?
The metal can be shaped into different forms
Describe the structure, forces and bonding in every element across period 2
Li and Be -> giant metallic; strong attraction between positive ions and delocalised electrons; metallic bonding
B and C -> giant covalent; strong forces between atoms; covalent
N2, O2, F2 and Ne -> simple molecular; weak intermolecular forces between molecules; covalent bonding within molecules and intermolecular forces between molecules
Describe the structure, forces and bonding in every element across period 3
Na, Mg, Al -> giant metallic; strong attraction between positive ions and delocalised electrons; metallic bonding
Si -> giant covalent; strong forces between atoms; covalent
P4, S8, Cl2, Ar -> simple molecular; weak intermolecular forces between molecules; covalent bonding within molecules and intermolecular forces between molecules
