Topic 6 - groups in the periodic table Flashcards
How are element arranged in the periodic table?
Ordered by increasing atomic number
Elements in the same group have the same number of outer shell electrons
Elements in the same period have the same number of electron shells
How many electrons are in the outer shell of a group 1 element?
1
Why do elements in the same group have similar chemical properties?
They have the same number of electrons in the outer shell
What group of the periodic table are the alkali metals?
Group 1
List two properties of alkali metals
Soft
Relatively low melting points
Why are group 1 elements called the alkali metals?
They react with water to form alkaline solutions
Why should alkali metals be stored in oil?
To prevent them reacting with water vapour and oxygen in the air
What is the order of reactivity of the first 3 alkali metals with water?
Lithium
Sodium
Potassium
Predict the reactivity trend down group 1
Increases down group 1
Why does reactivity increase down group 1?
The number of electron shells increases so there is more electron shielding
There is a weaker attraction between the positive nucleus and outer shell electrons so it is easier to remove an outer shell electron to form a positive metal ion
What groups are the halogens in? Why?
Group 7 because they have 7 outer shell electrons
What is the colour and state of chlorine at room temperature?
Pale green gas
What is the colour and state of bromine at room temperature?
Red-brown liquid
What is the colour and state of iodine at room temperature?
Black solid
Why are the halogens at different states at room temperature? What is the trend down the group?
Chlorine is gas, bromine is liquid and iodine is solid because they have different melting points
As you go down, the melting and boiling points increase
Why does melting and boiling point increase down group 7?
The molecules get bigger so there are more intermolecular forces to overcome during melting/boiling so more energy is required
What is the chemical test for chlorine?
Damp litmus paper placed into a test tube of gas. If chlorine is present, the litmus paper will turn red then white due to the bleaching effect of chlorine
What does diatomic mean?
Substances that form molecules consisting of 2 atoms