C6: Groups In The Periodic Table Flashcards
How are elements arranged in the periodic table?
Ordered by increasing atomic number.
Elements in the same group (column) have the same number of outer shell electrons.
Elements in the same period (row) have the same number of electron shells.
How many electrons are in the outer shell of a group 1 element?
One
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?
- Relatively low melting points
- Soft
Why are group 1 elements called the alkali metals?
They react with water to form alkaline solutions (pH greater than 7).
What are the products of the reaction between lithium and water?
Lithium hydroxide and hydrogen.
Why should alkali metals be stored in oil?
To prevent them reacting with water vapour and oxygen in the air.
What would be observed when lithium reacts with water?
- Slowest reaction of the alkali metals.
- Bubbles of hydrogen are produced.
- Doesn’t melt (highest melting point of alkali metals).
What would be observed when sodium reacts with water?
- Faster reaction than lithium.
- Floats on the surface of water (less dense than water).
- Bubbles of hydrogen are produced which cause the sodium to whizz around the surface of the water.
- Melts as enough energy is given out to meet sodium’s melting point.
What would be observed when potassium reacts with water?
- More violent reaction than sodium.
- Bubbles of hydrogen are produced which cause the potassium to whizz around the surface of the water.
- Melts into a shiny ball.
- Burns with a lilac flame.
What is the order of reactivity of the first 3 alkali metals with water?
Lithium reacts least violent reaction, potassium reacts most violently:
Lithium < Sodium < Potassium
Using the reactions of the first 3 alkali metals with water, predict the reactivity trend down group 1?
Reactivity increases down group 1.
Why does reactivity increase down group 1?
The number of electron shells increases down the group so there is more electron shielding. As a result, there is weaker attraction between the positive nucleus and outer shell electron. This means it is easier to remove an outer shell electron to form a positive metal ion.
Which group 1 element would you expect to react most violently with water?
Reactivity increases down the group so francium will react most violently with water.
What group 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?
At room temperature, chlorine is gaseous, bromine is liquid and iodine is solid because they have different melting and boiling points. As you go down the group, melting and boiling point increases.
What state would you expect the halogens fluorine and astatine to be at room temperature?
Fluorine is above chlorine so should have a boiling point lower than chlorine. This means it would be a gas at room temperature.
Astatine is below iodine in group 7 so should have a higher melting point than iodine. Therefore you can predict that it would be a solid at room temperature.
Why does melting and boiling point increase down Group 7?
The molecules get bigger down the group so there are more intermolecular forces to overcome during melting / boiling so more energy is required.
Halogens are diatomic. What does this mean?
They form molecules consisting of 2 atoms
What charge does a halide ion carry? Why?
-1
They gain 1 electron to have a stable outer shell
