Periodic table Flashcards
Give 3 features of the first periodic table
.Ordered by atomic weight
.contained gaps
.Sometimes, the order was changed so that elements with similar properties were in same group
What tends to happen to metal elements
They lose electrons to form positive ions
Why is helium a noble gas with only 2 electrons in its outer shell
It is the first shell so can hold a maximum of 2 electrons making it stable
Does the reactivity of alkali metals increase up or down the group
Down
What is formed when you react sodium with water
Sodium hydroxide AND hydrogen
What is formed when you react lithium with oxygen and where
Lithium oxide on the surface of the alkali metal
How would you describe an alkali metal’s ionic compound
Usually white or colourless crystals that produce colourless solutions when dissolved in water
Describe the properties of a halogen molecule
.There is a single covalent bond between the atoms in the molecule
.Halogens always exist as small molecules
Give 3 properties of alkali metals
.soft solids
.low melting and boiling points
.low densities (some float on water)
Why are alkali metals stored in oil
They are very reactive and must be kept away from water/oxygen
What happens when an alkali metal reacts with water
It forms hydrogen and a metal hydroxide
What happens in a reaction between an alkali metal and chlorine
They react vigorously and Salts that are white or colourless crystals are formed
Give 3 properties of metal hydroxides produced from alkali metal + water
.The metal hydroxide will always be alkali
.They are all soluble in water
.They form a colourless solution
What state are these 4 halogens in at room temperature: A: fluorine B: Chlorine C: Bromine D: Iodine
A: pale yellow gas
B: green gas
C: red/brown liquid
D: grey solid
What happens to the reactivity of halogens down the group
It decreases
Describe the melting points, boiling points and conductivity of halogens
.Low melting and boiling points
.Poor thermal and electrical conductors
How could one show that chlorine is more reactive than bromine
Add chlorine to [soluble] bromide solution and bromine will be displaced
Why do halogens have low melting and boiling points
They are small molecules with only a single covalent bond between the halogen atoms in their molecules
Why do halogens become less reactive down the group
.Halogens react by gaining electrons
.As atoms get larger down the group there is less attraction due to shielding so it is harder to gain electrons
Why are metals more reactive the further down the group
.React by losing electrons
.Larger atoms have more shells so more shielding blocking outer shell electrons from positive nucleus charge
.Outer shell electrons more easily lost so more reactive
How are elements in the periodic table ordered
Atomic number
Why do elements in the same group have similar chemical properties
They have the same number of electrons in their outer shell
?
?
No
No
Why don’t noble gases form molecules easily
Their atoms have a stable arrangement of electrons
What happens to the boiling point of noble gases down the group
It increases
How do chlorine, bromine and iodine react with iron wool
All: produce flames
Chlorine - reacts very quickly
Bromine - must be heated as well as iron —> relatively slow
Iodine - both must be heavily heated —> very slow
