46 terms

iGCSE Chemistry: Alkali metals & Halogens - core

STUDY
PLAY
How are elements arranged in the periodic table?
in order by atomic number
On the Periodic table what is the meaning of the word Group?
A Group is a vertical column of similar elements
On the Periodic Table what is the meaning of the word Period?
A Period is a horizontal row of elements
How many electron shells do the elements in the third period have?
3
How many electrons can the first, second and third shells hold?
First 2, second 8, third 8
How many electrons in a calcium atom?
20
How many electrons in the outer shell of group 7 elements?
7
Write the electronic configuration of potassium
2,8,8,1
Are metal oxides acidic or basic?
Basic
Are non-metal oxides acidic or basic?
Acidic
If an element doesn't conducts electricity, is it a metal or a non-metal?
Non-Metal
Where are non-metals found on the periodic table?
At the top right, plus hydrogen
Why do elements in the same group of the periodic table have similar chemical properties?
Elements in the same group of the periodic table have the same number of electrons in their outer shell
Explain, in terms of the arrangement of electrons in its atoms, why neon is very unreactive
Neon has 8 electrons in the outer shell, so it is full. Therefore it does not easily gain or lose electrons
What are the elements in group 0 called?
Noble gases
What is special about the elements in group 0?
They are very unreactive (because they have full outer electron shells)
State 4 observations when sodium reacts with water
1) fizzing occurs 2) sodium moves around 3) sodium melts 4) sodium disappears 5) sodium floats
State 5 observations when potassium reacts with water
1) fizzing occurs 2) potassium moves around 3) potassium melts 4) lilac flame is seen 5) potassium disappears 6) potassium floats
What are the elements in group 1 called?
Alkali metals
Write the chemical equation for the reaction betweem sodium and water
2Na + 2H₂O → 2NaOH + H₂
If pieces of lithium, potassium and sodium were added to water, how could observations of the differences reactions indicate the relative reactivity of those 3 metals?
Lithium would bubble the least vigorously, showing it is least reactive. Potassium would give off a lilac flame, showing it is most reactive.
If pieces of lithium, potassium and sodium were cut and exposed to air, how could observations of the differences reactions indicate the relative reactivity of those 3 metals?
Potassium would oxidise the most quickly, showing it is most reactive. Lithium would oxidise the slowest, showing it is least reactive.
Describe the relative reactivities of the elements in Group 1
The reactivity increases as you go down the group, e.g. Li<Na<K<Rb
(Triple only) Explain, by referring to the electronic configurations, why lithium is less reactive than sodium.
Sodium has the electronic configuration 2,8,1 and lithium has 2,1. The outer electron lost from sodium is further from the nucleus therefore the electron is less attracted by the nucleus. So sodium is more reactive than lithium
What are the elements in group 7 called?
Halogens
What colour and state is bromine at room temperature?
red-brown liquid
What colour and state is iodine at room temperature?
dark grey solid
What is the colour and physical state of chlorine at room temperature?
Green gas
Predict what colour and state is astatine at room temperature
black solid
Predict what colour and state is fluorine at room temperature
yellow gas
Suggest how the reactivity of fluorine compares to chlorine
Fluorine is more reactive than chlorine as it is higher in the group.
Describe how reactivity changes as you descend group 7
decreases
Hydrogen bromide is reacted with chlorine to form bromine. Write a chemical equation.
2HBr + Cl₂ → 2HCl + Br₂
Identify the element that is displaced in this reaction: 2HBr + Cl₂ → 2HCl + Br₂
Bromine
Name the substance with the brown colour that forms whem chlorine is added to potassium iodide solution
Iodine as it is less reactive than chlorine
State the colour change observed when bromine is added to an aqueous solution of potassium iodide
Colourless to brown
What type of reaction occurs if you put a chlorine with a solution of sodium bromide?
displacement
Why does chlorine react with hydrogen bromide?
Chlorine is more reactive and so displaces the bromine.
(Triple only) Explain why bromine is less reactive than chlorine
Both chlorine and bromine react by their nucleus attracting an electron to fill their outer shell. The outer shell of bromine is further from the nucleus, so the attraction is weaker, making it less reactive.
(Triple only) Explain, by referring to the electronic configurations, why fluorine is more reactive than chlorine
Fluorine has the electronic configuration 2,7 and chlorine has 2,8,7. An extra outer electron is gained more easily by fluorine. This is because the outer shell is closer to the nucleus, so an extra electron is attracted more strongly.
A gas is bubbled through limewater and the limewater goes cloudy. Identify the gas.
Carbon dioxide
Describe the test for ammonia gas
Turns damp red litmus paper blue
Describe the test for carbon dioxide gas
Bubble the gas through limewater and see if it goes cloudy
Describe the test for chlorine gas
Turns moist litmus paper white (bleaches)
Describe the test for hydrogen gas
Use a lit splint to see if the gas pops
Describe the test for oxygen gas
Use a glowing splint and see if it relights
OTHER SETS BY THIS CREATOR