C4.1 Predicting Chemical Reactions Flashcards
What are the elements in group 1 known as?
The alkali metals
Why are group 1 elements called alkali metals?
Because they react with water to form alkaline solutions
What are some properties of group 1 elements (alkali metals)
They are:
- shiny when freshly cut
- good conductors of electricity
- solid at room temperature
- soft (gets softer as you go down the group)
- density increases going down the group
- melting point decreases going down the group
Does the density increase or decrease going down group 1?
Increase
Does the melting point increase or decrease going down group 1?
Decrease
Why are group 1 elements usually stored in oil?
To prevent them from reacting with oxygen in the air and with water
What is the general word equation for what happens when an alkali metal reacts with water?
Alkali metal + water —> metal hydroxide + hydrogen
Does the reactivity of alkali metals increase or decrease going down the group?
Increase
What would you see when lithium reacts with water
It fizzes and slowly disappears
What happens to sodium when it reacts with water
It melts to form a silver ball, fizzes and then disappears
What happens when potassium reacts with water?
It would immediately ignite, burn with a lilac flame and then disappear
Why do group 1 elements have similar chemical properties?
Because all of their atoms have one electron in the outer shell.
Are the elements in group 7 metals or non-metals?
Non-metals
What are some properties of group 7 elements
Brittle
Poor conductors of electricity
Exist as diatomic molecules
What colour is fluorine
A pale yellow gas
What colour is chlorine
A green gas
What colour is bromine
An orange-brown liquid that vaporises easily
What colour is iodine
A shiny grey-black crystalline solid that sublimes to form a purple vapour
Going down group 7:
Density increases
Melting point and boiling point increases
What are group 7 elements known as
The halogens
What does halogen mean
Halos - salt
Gen- maker
Halogen - salt maker
Why are group 7 metals called halogens ?
Because they react with metals to produce salts
Does the reactivity of the halogens increase or decrease going down the group?
Decrease
Why do halogens have similar chemical properties?
All their atoms have 7 electrons in their outer shell. They gain an electron in reactions forming ions with a single negative charged (-1).
X2 +2e- —> 2X-
What does crystalline mean?
The structure of substances in the solid state that gave particles arranged in a giant lattice
What is density?
The mass per unit volume
What is a halide?
A halide is a compound containing group 7 elements and one other element (usually hydrogen or a metal).
What are the elements in group 0 known as?
The noble gases
Why are the group 0 elements called noble gases?
Because they are so unreactive.
Like how the noble men and women of the past who didn’t take part in ordinary everyday activities, the noble gases take part in very few reactions.
Why are the noble gases so unreactive?
Because they all gave complete outer electron shells.
This means they don’t lose or gain electrons to form ions in reactions or share electrons to form molecules in a reaction .
What properties do noble gases have?
- low densities
- monatomic
- low boiling point
Going down the group:
-boiling point increases
- attractive forces between atoms get stronger
- density increases
Why do noble gases have low boiling points?
They are monatomic.
They exist as single atoms with very weak forces of attraction between them. These forces of attraction are easily overcome by heating which gives the noble gases low boiling points.
Why do noble gases have relatively low densities?
Their atoms are far apart in the gas state so there is very little mass in a given volume
Why does the boiling point increase going down the group?
- the atoms become larger
- intermolecular forces between the atoms become stronger
- more energy is needed to overcome these forces
What are some uses of helium? Why is it used for this?
Helium is used as a lifting gas in party balloons and airships
This is because helium is:
- less dense than air, so balloons and airships ride
- non flammable do the helium cannot set on fire.
What is a use for Argon and why is it used for this ?
Argon is used as a ‘shielding gas’ when welding pieces of metal together.
Argon is:
- denser than air so it stops air getting to the metal
- inert so the hot metal cannot oxidise and spoil the weld.
Filament lamps contain thin metal wires. These become very hot and glow brightly when an electric current is passed through them. why are argon, krypton or xenon used in these lamps
The hot metal wires will burn if any oxygen from the air is present in the lamp.
Argon, Krypton and Xenon are very unreactive
They replace the air inside the lamp, preventing the metal wire from burning away
Where are the transition metals placed in the periodic table?
Between groups 2 and 3 (IUPAC groups 2 and 13)
What are some properties of transition metals?
They are:
-shiny
- good conductors of electricity
- strong
- malleable
Compared to the alkali metals of group 1, the transition metals are:
Transition metals are :
- stronger and harder
- have higher densities
- have higher melting points
- less reactive than alkali metals
What can transition metals be used as?
Catalysts
What are some uses of transition metals?
They can be used to make everyday objects
Platinum, rhodium and palladium are used in catalytic converters
What are the products of the reaction between iron and oxygen
Rust (hydrates iron(iii) oxide)
Do gold, platinum and iridium react with oxygen or water
No
Examples of Catalytic activity in transition metals
Iron is the catalyst in the haber process (to make ammonia)
Maganese (IV) oxide increases the decomposition of hydrogen peroxide
What happens in a halogen displacement reaction?
A halogen displaces a less reactive halogen from its halide ions in solution
How do you carry out a halogen displacement reaction
- Use a pipette to add a few drops of potassium chloride solution (KCl) to a column of three wells in a spotting tile
- Repeat step 1 with potassium bromide solution and potassium iodide solution.
- Use a dropping pipette to add a few drops of chlorine solution to a row of three wells in the spotting tile
- Repeat step 3 with two more rows of wells using bromine solution then iodine solution
What is a halide ion?
A negative ion formed by a group 7 element
Do metals form positive or negative ions in reactions?
Positive ions
Does a metal have to be more reactive than hydrogen to react with water or acids?
Yes
List the metals on the reactivity series (most reactive to least reactive)
Potassium Sodium Calcium Magnesium Aluminium Zinc Iron Tin Lead (Hydrogen) Copper Silver Gold Platinum
The more reactive the metal…
The greater the rate of hydrogen production
The more easily metals form positive ions in reactions…
Th more reactive they are
Why do you not boil water or hydrochloric acid during reactions with metals
Because you won’t be able to tell if the bubbles are due to heating or due to the reaction.
It is unsafe to boil dilute HCl
A more reactive metal displaces a less reactive metal from solutions of its compounds. True or false
True
What type of reactions are displacement reactions?
Redox reactions
Elements in group 0…
Do not react
Reactive non metals…
Form covalent compounds with each other
Metals and reactive non-metals…
Form covalent compounds with each other
Metals in group 1 and 2…
Are more reactive than transition metals and other metals
Non metals in group 7…
Become less reactive down the group
