Groups In The Periodic Table Flashcards
What are group 7 elements known as?
Alkali metals
Why do the alkali metals have similar chemical properties?
They all have one outer electron
What are the physical properties of group 1 elements?
Low melting and boiling points
Soft
What do alkali metals form?
Ionic compounds
They lose their single outer electron so easily they cannot share it- they don’t form covalent bonds
Why are group 1 elements very reactive?
They readily lose their single outer electron to form a 1+ ion with a stable electronic structure
What happens to the reactivity going down group 1?
It increases
Why does reactivity increase going down group 1?
The outer electron is easily lost as its further from the nucleus (larger atomic radius) so its less strongly attracted to the nucleus and less energy is needed to remove it
What happens when group 1 elements are put in water?
They react vigorously
Hydrogen gas and a hydroxide of the metal are produced
What are group 7 elements known as?
Halogens
Why do group 7 elements have similar chemical properties?
They all have 7 electrons in their outer shell
What do the halogens exist as?
Diatomic molecules (eg Cl2)
How do the halogens gain a full outer shell?
They share a pair of electrons in a covalent bond
What physical properties do the halogens have?
The melting and boiling points increase Colour gets darker At room temperature: Chlorine= green gas Bromine= red brown liquid Iodine= grey crystalline solid
How is chlorine tested for?
Using damp blue litmus paper
Chlorine will bleach the paper and turn it white
It may turn red for a second because chlorine is acidic
What happens to reactivity going down group 7?
It decreases
Why does reactivity decrease going down group 7?
It’s harder to attract the extra electron to fill the outer shell when its further away from the nucleus (the atomic radius is larger)
How does a halogen atom achieve a stable structure?
Gaining an electron to form a 1- ion
When halogens react with some metals, what forms?
Salts called metal halides
Why are halogens higher up group 7 more reactive?
They can attract the outer electron of the metal more easily
What forms when halogens react with hydrogen?
Hydrogen halides
Properties of hydrogen halides
Soluble
Form acidic solutions
Why do the halogens react with metals and hydrogen in similar ways?
They have the same number of electrons in their outer shells
What are group 0 elements known as?
Noble gases
What does ‘noble’ mean?
Unreactive
What are group 0 elements at room temperature?
Inert, colourless gases
Why are group 0 elements monoatomic?
Their gases are made up of single atoms (not molecules)
Why are the noble gases inert?
They don’t react
They have a full outer shell of electrons
Why are the noble gases non flammable?
They are inert
What are everyday uses of the halogens?
Provide an inert atmosphere
Argon does this in light bulbs
Argon krypton and xenon are used in flash photography
Argon and helium are used to protect metals being welded
Helium is used in airships and party balloons due to its low density and its non flammable
What are the patterns in the properties of the noble gases?
Boiling, melting points decrease going down group 0
Density decreases going down group 0
What elements take part in displacement reactions?
Group 7 halogens
What is a displacement reaction?
Where a more reactive element ‘pushes out’ (displaces) a less reactive element from a compound
What type of reaction are halogen displacement reactions?
Redox reactions
What happens to the number of electrons in halogens and halide ions during halogen displacement reactions?
Halogens gain electrons (reduction)
Halide ions lose electrons (oxidation)
What can displacement reactions show?
The reactivity trend of halogens
