Groups in the Periodic Table Flashcards
How are elements arranged in the periodic table?
Ordered by increasing atomic number
How many electrons are in the outer shell of a group 1 element?
One
Why do elements in the same group have similar chemical properties?
They have the same number of electrons in the outer shell
What group of the periodic table are the alkali metals?
Group 1
What are the properties of alkali metals?
Relatively low melting points and soft
Why are group 1 elements called the alkali metals?
They react with water to form alkaline solution
Why should alkali metals be stored in oil?
To prevent them reacting with water vapour and oxygen in the air
What would be observed when lithium reacts with water?
Slowest reaction of the alkali metals, bubbles of hydrogen are produced and doesn’t melt
What would be observed when sodium reacts with water?
Faster reaction than lithium, floats on the surface of water, bubbles of hydrogen are produced which cause the sodium to whizz around the surface of the water and melts as enough energy is given out to meet sodium’s melting point
What would be observed when potassium reacts with water?
More violent reaction than sodium, bubbles of hydrogen are produced which cause the potassium to whizz around the surface of the water, melts into a shiny ball and burns with a lilac flame
What is the order of reactivity of the first 3 alkali metals with water?
Lithium < Sodium < Potassium
What is the prediction of the reactivity with water trend down group 1?
Reactivity increases down group 1
Why does reactivity increase down group 1?
The number of electrons shells increases down the group so there is more electron shielding, there is weaker attraction between the positive nucleus and outer shell electrons, thus means it’s easier to remove an outer shell electron to form a positive metal ion
Which group 1 element would you expect to react most violently with water?
Reactivity increases down the group so francium will react most violently with water
What groups are halogens in?
Group 7 because they have 7 outer shell electrons
What is the colour and state of chlorine at room temperature?
Pale green gas
What is the colour and state of bromine at room temperature?
Red-brown liquid
What is the colour and state of iodine at room temperature?
Black solid
Why are halogens at different states at room temperature?
They have different melting and boiling points and as you go down the group, melting and boiling point increases
What state would expect the halogens fluorine and astatine?
Fluorine: gas and Astatine: solid
Why does melting and boiling point increases down group 7?
The molecules get bigger down the group so there are more intermolecular forces to overcome during melting/boiling so more energy is required
What is the chemical test for chlorine?
Damp litmus paper placed into a test tube a gas, if chlorine is present, the litmus paper with turn red then white due to the bleaching effect of chlorine
What does halogens are diatomic mean?
They form molecules consisting of 2 atoms
What charge does a halide ion carry?
-1, they gain one electron to have a stable electron configuration
What is produced when a halogen reacts with a metal?
Metal halide salt
What is the trend in reactivity of the halogen?
Reaction decreases down group 7, rate of reaction decreases down group 7
What is formed when hydrogen reacts with a halogen?
Hydrogen halides
Why does chlorine reacts with hydrogen in the presence of sunlight but bromine requires a flame?
Reactivity decreases down the group so bromine requires more energy for the reaction to occur
What is formed when a hydrogen halide dissolves in water?
An acidic solution, hydrogen ions dissociate, making the solution acidic
What is the prediction of the product of the reaction between hydrogen and fluorine?
Hydrogen fluoride
When does a halogen displacement reaction occur?
When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide
Which halogens can chlorine displace from an aqueous ionic solution?
Any halogens below it in group 7
Which halogens can’t chlorine displace from an aqueous ionic solution?
Any halogens above it in group 7
Which halogens would you expect astatine to be able to displace?
None
Why does reactivity decrease down group 7?
As you down group 7, the outer shell is further from the nucleus and electrons shielding increases, attraction between the nucleus and outer electrons decreases so it’s harder for the atom to gain an electron meaning reactivity decreases
What colours are solutions of chlorine, bromine and iodine?
Chlorine water: colourless, Bromine water: orange and Iodine solution: brown
What is a redox reaction?
A reaction where oxidation and reduction take place at the same time
Why are halogen displacement reactions redox reactions?
The halide ion is oxidised to form a halogen atom and the halogen is reduced to form a halide ion
What name is used to describe the elements in group 0 of the periodic table?
Noble gases
How many electrons do the noble gases have in their outer shell?
0, they have no incomplete shells of electrons
What does chemically inert mean?
Not chemically active
Why are the noble gases chemically inert?
They have full outer electron shells, this is a very stable electron configuration and means the elements are very unreactive
What properties of helium makes it suitable for use in balloons?
It’s less dense than air and doesn’t burn
Why is argon used to fill electric light bulbs?
It’s very chemically inert so will not react when the light bulb gets hot, it’s non-flammable
Why is argon used for welding?
It provides an inert welding atmosphere, argon is more dense than air so keeps air away from the metal
What is the trend in boiling points down group 0?
Boiling point increases down group 0 because the relative atomic mass increases so there are more intermolecular forces between atoms
What is the trend in density down group 0?
Density increases down the group, helium is the least dense and radon is the most dense
