C2 Flashcards
How did John Dalton arrange the periodic table?
He arranged the elements in order of their atomic weights, which were measured in various chemical reactions.
What did John Newlands propose?
He arranged the known elements in order of mass but noticed the properties of every eighth element seemed similar. He produced his ‘law of octaves’ but believed all the elements were found so it didn’t make sense.
What did Dmitri Mendeleev propose?
He placed all the discovered elements in order of their atomic weights and arranged them so a pattern in properties could be seen. He also left gaps for elements undiscovered at the time.
What is the difference between metals and non-metals?
Metals conduct electricity while non-metals do not. Metals have a higher boiling and melting point. Metals are also ductile and malleable while non-metals are brittle.
What are the noble gases?
They are in group 0 and have a full outer shell (apart from helium) so they are very stable. They exist as single atoms(monoatomic) and have no tendency to react. Their boiling point gets higher as you move down the groups.
What are properties of the alkali metals?
They are very reactive. They have to be stored in oil to not react with the air. The reactivity increases going down the group. They all have low densities and are soft. They start shiny but go dull when they react with the oxygen in the air.
They have low boiling points for metals and going down the groups the boiling point goes lower. The hydroxides are all soluble in water and the solution is colourless with a high pH.
What are the alkali metals electronic structure like?
They have one electron in each outer shell which gives them similar properties. It also makes them very reactive as they only have to lose 1 electron to react. They react with non-metals and form a metal ion with a +1 charge. They always form ionic compounds.
How do the alkali metals react with water?
When you add lithium, sodium or potassium to water, the metal floats on the water, moving around and fizzing as the metal reacts with the water to give off hydrogen gas. Potassium ignites.
What other reactions can occur with the alkali metals?
They can react vigorously with non metals such as chlorine gas, producing metal chlorides. The reactions get more vigorous as you move down the groups as it is easier to lose the single electron in the outer shell with more shells.
What are the properties of the Halogens?
These are group 7 and are toxic non-metals. They have low melting points and boiling points. They both increase going down the group. They are poor conductors of heat and electricity. They exist as pairs, joined in a covalent bond, making a covalent compound.
What are the reactions of the halogens?
They get less reactive going down the group. When they react with non-metals they gain an extra electron by sharing a pair of electrons with another atom. They react with metals.
What are the displacement reactions between halogens?
The more reactive the halogen is than another means it will displace a less reactive halogen from a solution of one of its salts.
What is the trend of reactivity in groups?
When you go down the group, the number of shells increases so the atoms become larger as you go down. This can cause the larger atoms to lose electrons more easily going down a group or larger atoms to gain electrons less easily going down a group. This is due to the outer electrons being further away from the attractive force of the nucleus. The shells can also shield the outer electrons from the force.
What does the electrostatic attraction depend on?
It depends on the distance from the outer electrons and the nucleus, the number of inner shells providing a shielding effect and the size of the positive charge on the nucleus.
What are the physical properties of the transition metals?
They are good conductors of electricity and heat, they are hard and strong, they are dense and they have high melting points except mercury.
