Groups Of The Peridoic Table Flashcards
What are the properties of alkali metals?
Soft Low melting point Dull colour React with water and oxygen Gives of hydrogen
What group and charge are the alkali metals in?
1 so they all have a 1+ charge as they want to loose an electron to gain a full outer shell
-the more readily this is lost the more reactive it is
Why are alkali metals stored under oil?
As it stops them reacting with the oxygen in the air
Why are these elements called alkali metals?
Because they produce an alkali solution when reacted with water -hydrogen and metal hydroxide
Ph of 13/14
What happens to the trend of appearance as you go down the alkali metals group?
The inside stays shiny but the outside becomes a lighter version of black/grey
What is the trend of effervescing when reacted with water as you go down the alkali metals group?
The element effervesces (fizz) more, meaning more hydrogen is given off. It also moves around more as it is more reactive and potassium gives off a purple flame
What is the general equation to show an alkali metal reaction with water?
2Alkali metal + 2water — 2metal hydroxide + hydrogen
What is the affect of an alkali metal having more shells?
The more shells an atom has the further the outer shell electron is from the nucleus. This decreases the attraction between the outer shell electrons and the nucleus, so makes the alkali metal more reactive as the outer electron is easier to remove.
What happens to the size of the atoms as you go down the alkali metal group?
They get bigger as they have more electron shells.
What group and charge are the halogens in?
7 so they have a 1- charge as they want to gain an electron in order to create a full outer shell
-this means they have similar chemical properties and react similarly
What is the appearance and state if the first 3 halogens?
Chlorine = yellowy/green = gas Bromine = Brown/orange = liquid at room temperature Iodine = grey = solid
What happens to the trend pf the halogens and alkali metal boiling points as you go down the group?
Halogens =Their boiling points get higher
Alkali metals = boiling point decreases
What are the halogen molecules?
Diatomic so are written as (e.g. Cl2, Br2, I2)
-this is because by sharing a pair of electrons they gain a full outer shell
What is the test for chlorine gas?
That it turns light blue litmus paper red and then bleaches white
What do halogens make when they react with metals and hydrogen?
With metals they form Salts called metal halides
Or with hydrogen to form hydrogen halides (these can dissolve in water to form acidic solutions as they are Soluble)
How do you balance a metal halide reaction?
Cl2 (gas) + H2 (gas) — 2 HCl (gas)
What happens when hydrogen chloride is put into water?
Is dissociates into hydrogen ions (H+) and (Cl-)
Hydrogen chloride + water — hydro-chloric acid
What is a displacement reaction?
A displacement reaction happens when a more reactive element displaces a less reactive element
Why can chlorine displace bromine and iodine?
Because it is the most reactive halogen (top of the group)
This means if you add chlorine water to any of them it will displace it and be reduced while the other compound oxidised
Chlorine + potassium bromide —
Potassium chloride + bromine
Why do halogens become less reactive as you go down the group?
As you go down the group the elements have more outer shells so the outer most electrons are further away from the nucleus. This means it is harder to gain electrons as the attraction is weaker
What group are Nobel gases in?
8/0
Why does helium make your voice go high?
Because the speed of sound is faster in lighter gases
What are the properties of Nobel gases?
Colourless, odourless, tasteless Low melting point and boiling point Low density Inert (stable and un-reactive) Single atoms (monatomic) as they have a full outer shell
What does it mean if Nobel gases have a full outer shell?
This means they do not need to gain or lose an election is they were to react. This makes them stable and inert
What is the property of the Nobel gas helium for balloons?
As helium has a low density, even lower then air, it will float and rise into the air making it suitable for a balloon. It will also float without combusting making it safer than hydrogen
What is the property if the Nobel gas Neon making it suitable for lights?
Neon gives out ‘white’ light when high voltage electricity passes through it and so is useful as a source of light
What is the property that makes argon useful for filament bulbs?
- it isn’t flammable so it stops the very hot filament from burning away, flags photography uses this
- stops the filament reacting with the oxygen in the air, welding metals uses this process as well
What is the trend in reactivity of halogens as you go down the group?
The atoms get larger, so the attraction is weaker between the outer shell electrons and the nucleus. Therefore the less easily an electron is gained so the less reactive it is the further down you go.
What does OIL RIG stand for?
Oxidation is loss (of electrons)
Reduction is gain (or electrons)
What are the properties of transition metals?
- higher melting points and densities than other groups
- very ductile
- malleable
- less reactive so more useful
- can be used as catalysts
- solutions are colourful
Where are transition metals found?
In the middle rectangle if the periodic table
Transition metals form coloured compounds, how can we use this property?
To identify which transition metal is present in a solution
-they can also be used as dyes in products
What are some uses linked to properties of transition metals?
Copper is ductile and can conduct electricity making it useful for wires and frying pans
- aluminium might be used in mirrors due to its shiny property and in overhead cables as is less dense than e.g. copper so can hang in the air but is also resistant to corrosion so suitable for all weather
- gold is used in jewellery as is shiny, ductile and expensive
What are some uses of alloys?
Magnalium (95% aluminium, 5% magnesium) is less dense and four times stronger than normal aluminium having a better resistance to corrosion -used in aircraft parts
-brass is made of copper and zinc and is used in electrical plug pins as conducts electricity and is stronger than normal copper
What transition metals are used as catalysts?
- iron is used in the haber process
- vanadium pentoxide is used in the contact process
Why are alloys strong?
- normal metals have rows of regularly arranged metal cations that can slide over one another
- the presence of another size atom disrupts the regular arrangement so metals cannot slide and are stronger
- alloys can be designed for specific uses as well
- a mixture of a metal with one or more element
Why might one make an alloy?
- increase strength or ductility or resistance
- lower or increase the melting point
- change the colour
- give better castings (moulds)
- change electrical or thermal properties
Why is iron alloyed to produce steel?
- iron on its own will rust but by adding carbon is reduces this making it stronger and more resistant
- it is harder as can slide less easily
