Describe Mendeleev’s periodic table
- Ordered his table in order of atomic weight and adjusted for chemical properties
- left gaps for undiscovered elements, which when they were discovered, matched his predictions
Describe Newland’s periodic table
- ordered in order of atomic weight ONLY
- realised similar properties occurred every eighth element- “law of octaves” - broke down after calcium
- only included known elements
What are the properties of metals?
Shiny, good conductor, strong, malleable, ductile, high m.p
What are the properties of non-metals?
dull, poor conductor, brittle, low m.p
Metals and non metals either form positive or negative ions. Which forms which though?
metals - form positive ions
non-metals - form negative ions
What does group number show?
How many electrons in the outer shell
What does period number show?
How many shells the element has
How does the periodic table arrange elements?
based on their atomic number
Describe the halogens
- Exist as diatomic molecules (e.g F2, Cl2)
- More reactive halogen can displace another halogen from a compound
In the halogens, does reactivity increase or decrease down the group?
decrease
In the halogens, does boiling point, melting point and density increase or decrease down the group?
increase
How reactive are the Noble Gases?
VERY unreactive
Does the boiling point of the noble gases increase or decrease down the group?
increase
Compare the transition metals and the alkali metals
- transition metals are harder, stronger, denser and have higher melting points
- transition metals are much less reactive with oxygen and water
- Transition metals form coloured compounds, alkali metals form white compounds
Which group are often used as catalysts?
Transition metals
Why are group 1 metals called “Alkali metals”
- they produce an alkaline solution when reacting with water
Does density and reactivity of group 1 increase or decrease down the group?
Increase
Does melting point of group 1 increase or decrease down the group?
decrease
Group 1 elements react vigorously with chlorine to form ____ which dissolve in water to form _____
- chlorides
- colourless solutions
Group 1 elements react with oxygen to form ______
metal oxides
Group 1 elements react with water to produce ____
a metal hydroxide and hydrogen
Why does reactivity increase as you go down group 1?
- group 1 are metals, so outer electron is lost
- atoms get larger as you go down
- so the outer electron gets further from the nucleus, and there’s more shielding
- attraction between nucleus and outer electron gets weaker, so the electron is lost more easily
Why does reactivity decrease as you go down group 7?
- group 7 are non metals, so they gain an electron
- atoms get larger down the group
- outer electron shell gets further from the nucleus as you go down, so there’s more shielding
- attraction between nucleus and outer shell gets weaker going down the group, so it’s harder to gain an electron
In Group 7, why does melting point increase as you go down the group?
-molecules increase in size going down group
-intermolecular forces increase
- so melting point increases
