Topic 4 - Groups in the Periodic Table Flashcards
What is the middle block of elements called?
The Transition Metals
What are metals made up of?
Positive metal ions surrounded by a sea of delocalised electrons. The ions attract the electrons to make strong metallic bonds.
What is the structure of metals?
- Metallic bonding
- A regular arrangement of a giant structure of positive ions with free electrons.
What are delocalised electrons ?
- Free (spare) electrons, that move freely through the structure.
What are the two common properties of metals and transition metals?
- They are malleable (Bendy)
- They are good conductors of electricity
- High melting points
- Colourful compounds (e.g. copper sulfate is blue/green colour)
- High Boiling points
Why are transition metals good conductors of electricity?
- As the delocalised electrons are free to carry the electric charge
Why can metals be bent into different shapes so easily?
- Due to the layers of atoms that slide over each other.
- Malleability.
What is the name for Group 1?
The alkali metals
What properties do alkali metals have ?
- They are soft
- They have low melting points
What is the rule linking reactivity to atomic numbers?
As the atomic number increases the elements become more reactive
When lithium, sodium or potassium are put in water and they react vigorously, what do they form?
Hydroxides
An alkali metal that reacts with water, produces what gas?
Hydrogen
What is the test for Hydrogen?
- Squeaky pop
- A lighted splint into a test tube of gas will ignite the hydrogen
What is the word equation for the reaction of an alkali metal with water?
alkali metal + water > metal hydroxide + hydrogen
What is the name of Group 7 ?
The halogens
How many electrons do they have in their outer shell?
7
What are the similar properties of Halogens at room temperature?
- Flourine = Yellow gas
- Astatine = Black solid
- Chlorine = Dense green gas
- Bromine = Orange Liquid
- Iodine = Dark grey solid
When Halogens react with metals what do they form?
Metal Halides
When Halogens react with hydrogen what do they form?
Hydrogen Halides
Are hydrogen halides soluble or insoluble?
Soluble
As hydrogen halides are soluble they dissolve to form what ?
Acidic solutions E.g. Chlorine + hydrogen > Hydrogen chloride (Hydrogen chloride dissolves to form hydrochloric acid)
As you go down the group does reactivity go up or down?
Down (They become less reactive)
Why do elements become more reactive the less shells they have?
The outer shell is nearer to the nucleus.
What is a displacement reaction?
When a more reactive halogen reacts with a solution containing halide ions it will ‘push out’ the less reactive halogen
If chlorine reacts with potassium iodide what gets displaced and what is formed? Give the equation.
The chlorine is more reactive so displaces the iodine. Chlorine therefore reacts with potassium iodide to form potassium chloride and iodine. Cl2 + 2KBr > Br + 2KCL
What is Group 0 called?
The noble gases
Why are elements in Group 0 unreactive?
They have full outer shells
As you go down the group do boiling points increase or decrease?
They increase
As you go down the group do densities of the elements increase or decrease?
They increase
What is the everyday use of Argon?
Used in light bulbs as its non reactive and not flammable
What is the everyday use of Helium?
Used to fill up balloons as it has a low density which makes balloons float.
How were the Noble gases discovered?
Chemists noticed that the nitrogen in the air was heavier than expected, so they hypothesised that there must be other gases in air. They found the Noble Gases through experiments including fractional distillation of air.
Why do trasnition metals have high melting and boiling points?
Due to their strong metallic bonds which needs lots of energy to break
