The Periodic Table Flashcards
What were the two ways to categorise elements until recently?
- Physical and chemical properties
2. Relative Atomic Mass
How did Newlands arrange the elements?
In rows of seven.
Why did Newlands arrange the elements in octaves?
He noticed that every eighth element had similar properties.
Why did Newlands table not work?
The transition metals messed up the pattern.
Why was Newlands’ work criticised?
- Elements that didn’t have similar properties were grouped together
- Non-metals and metals were mixed
- No gaps left for undiscovered elements
How many known elements were there in Mendeleev’s time?
Around 50.
How did Mendeleev arrange the elements?
In order of atomic mass.
Why was Mendeleev’s table successful?
Newly discovered elements fitted into gaps that he left.
Why were the gaps clever?
They predicted the properties of undiscovered elements.
Why was the periodic table largely seen as unimportant when it was first released?
There wasn’t much evidence to suggest that the elements really did fit together like that.
Why is there less attraction for electrons in higher energy levels?
- Increased distance
2. Increased shielding (other inner electrons)
Why does increased distance and shielding mean in terms of reactivity?
Outer shell electrons are more easily lost, but it’s harder for high energy levels to gain electrons.
What are the group one elements also known as?
Alkali metals.
How do the elements change as you go down group 1?
- More reactive
2. Lower melting and boiling points
What properties do alkali metals share?
- Low density
- One outer electron
- React with water to produce hydrogen gas
- Form ionic compounds with non-metals
What kind of ion do alkali metals form?
1+ ions.
What colour compounds do alkali metals form with non-metals, and what colour solutions?
White compounds that dissolve in water to form colourless solutions.
What is produced in the reaction between water and alkali metals?
- Hydrogen gas
2. Hydroxides - alkaline solutions
What happens when alkali metals are put in water?
- Float
- Move around surface
- Fizzing
What are the group seven elements also known as?
Halogens.
How do the elements change as you go down group 7?
- Less reactive
- Higher melting point
- Higher boiling point
What kind of elements are the halogens?
Non-metal coloured vapours.
What kind of bonds do the halogens form with metals?
Ionic bonds.
What kind of ions do the halogens form?
Halide ions (1-)
How do halogens react with other halogens in an aqueous solution of its salt?
More reactive halogens displace less reactive halogens.
What properties do transition metals share?
- Good conductors of heat and electricity
- Dense, strong, shiny (more than alkali metals)
- Less reactive (than alkali metals)
- Higher melting points (than alkali metals)
What is special about the ions that transition metals form?
They often have more than one ion.
Why are compounds colourful?
Due to the transition metal ion they contain.
What colours do transition metal ions give?
- Gemstones
2. Pottery glazes
What other use do transition metals have?
Good catalysts (e.g iron, Haber process)
