C3.1 Flashcards
What are the melting and boiling points like for alkali metals?
They’re low, and decrease as you go down the group
What are the melting and boiling points like for halogens?
They’re low, and increase as you go down the group
How are elements arranged in the periodic table today?
By their atomic number and in groups that have similar properties
Alkali metals form hydroxides that do what?
Dissolve in water to form alkaline solutions
Why are elements in group 1 more reactive as you go down the group?
~ Outer electron is further from nucleus
~ Weaker force of attraction
~ Less shielding of force from inner electrons
~ Electrons lost more easily
Why are elements in group 7 less reactive as you go down the group?
~ Outer electron is further from nucleus
~ Weaker force of attraction
~ More screening from inner electrons
~ Electrons gained less easily
What are some properties of the alkali metals?
~ Low melting/boiling points
~ Low density
~ React with water, releasing hydrogen
~ Soft
What are some properties of the halogens?
~ Poor conductors of heat and electricity
~ Poisonous
~ Produce coloured vapours
~ A more reactive halogen displaces a less reactive halogen from an aqueous solution of salts
What are some properties of transition metals compared to alkali metals?
~ Higher melting/boiling points ~ Harder and stronger ~ More dense ~ Less reactive, incl. with water and oxygen ~ Used as catalysts
How did Newlands arrange the periodic table?
~ He arranged them in order of atomic mass
~ Noticed similar properties in every eighth element
~ He hadn’t left spaces for undiscovered elements
How did Mendeleev arrange the periodic table?
~ Arranged the elements in groups
~ Left spaces for undiscovered elements by predicting their atomic masses and properties
Why do lithium, sodium and potassium float on cold water?
Because of their low density
What is produced when alkali metals react with water?
A metal hydroxide and hydrogen
What is different about Mercury?
It’s liquid at room temperature
What are properties of halogens as solids?
Brittle and crumbly
