C4 Flashcards
In 1897 what did JJ Thomson discover about atoms?
That the contain even smaller subatomic particles called electrons
In 1911, what did Ernest Rutherford discover about the atom?
That it is mostly empty space and that its electrons are arranged around a central object call a nucleus
What is the nucleus made out of?
Protons and neutrons
What does the atomic number of an element represent?
How many protons it contains
The top number is the relative atomic mass, what does it represent?
How many protons and neutrons in a element
What is an isotope?
Variations of an element that have the same atomic number (number of protons and electrons). But a different relative atomic mass (neutrons)
What is an ion?
An atom that has lost or gained electrons
In 1803, What did john dalton suggest about atoms? (2)
- all matter is made up of atoms
- atoms cannot be made or destroyed
- atoms in an element are all identical
- atoms on different elements are different
What is a element?
A substance that contains only one type of atom
What is a compound?
A substance that contains two or more elements and are chemically combined
Why is the name used to describe the way electrons are arranged in a atom?
Electronic structure
Give he mass and electronic charge of a neutron, proton and electron
Proton: mass. 1. Charge +1
Neutron: mass. 1. Charge 0
Electron : mass. 0.0005. Charge -1
What is a molecule?
A particle made up of two or more atoms chemically bonded together
What happens when a metal reacts with a non metal?
Electrons pass from the metal to the non metal. The positive metal ions and the negative non metal ions are then attracted to each other , forming ionic bonds.
Magnesium oxide and sodium chloride have high …..
Melting points
Sodium chloride ____ in water however magnesium oxide does not
Dissolves
What is the name of the arrangement of the ions in sodium chloride and magnesium oxide?
Giant ionic lattice
In a giant ionic lattice, the _____ ions are strongly attracted to the _____ ions, forming ___.
- Positive/negative
- Positive / negative
- Ionic bonds
What is needed for an ionic bond to conduct electricity and when can this happen?
It’s ions must be free to move and can happen in a molten liquid
Metals and non metals react together to form ionic bonds. What to non metals form when they react with each other?
Covalent bonds
What do group 1 element form when they react with water?
Alkaline solutions
What is the word equation for sodium reacting with water?
Sodium + water –> sodium hydroxide + hydrogen
As you go down group 1 in the periodic table the reactivity _____
Increases
What colours do lithium , sodium and potassium go in a flame test?
Lithium-red
Sodium - orange
Potassium - lilac
The group 7 elements are?
Halogens
What do halogens form when they react with a metal?
Salts (+ metal halides)
What does chlorine do?
Sterilises water and can be used for pesticides
Give te different states of chlorine bro in and iodine at room temperature
Chlorine- green gas
Bromine- orange liquid
Iodine- grey solid
How do you get a metal halide?
By reacting a halogen (group 7 element) with a metal
As you go down the periodic table in group 7 the reactivity ____
Decreases
When do displacement reactions occur?
When a group 7 element reacts with a metal halide
What happens in a displacement reaction?
The more reactive element displaces (pushes out) the less reactive element
The equation below is a displacement reaction, give the products
chlorine + sodium bromide
-> bromine + sodium chloride
What are precipitation reactions used for?
To identify transition metal ions in a solution
What is the insoluble solid called that is formed from the precipitation reaction?
The precipitate
How can we identify different transition metal ions in precipitation reactions?
Because different metal ions give different coloured precipitates
When a transition element compound dissolves in water its metal ions spread out. These ions then react with hydroxide ions to form metal hydroxide precipitates. What the colours of the metal hydroxide precipitates copper (II), iron (II) and iron (III)?
Copper- blur
Iron 2 grey- green
Iron 3 orange brown
Many metals have a high ___ strength
Strength
What does a high tensile strength mean?
They can resist being stretched
Explain why metals have high melting and boiling points using ideas about metallic structure.
Metals contain positive metal ions packed closely together. They become positive when their electrons leave the outer shell of the atoms. The electrons become free to move within the structure of the metal (delocalised electrons). The strong attraction between the positive metal ions and the delocalised electrons require a large amount of energy to break, which is why metals have such high melting and boiling points.
Resistance decreases as temperature decreases. At low temperatures some metals become ______
Superconductors
Name some uses of superconductors
- used for very string electromagnets that can be used in MRI scanners
- super fast electric circuits that can lead to extremely powerful computers
What is a benefit of using superconductors instead of traditional metal cables in the national grid?
They have very little or no resistance and therefore little or no energy is wasted
What is the drawback of superconductors?
An extremely low temperature is needed means that the application of superconductors is limited
Name the different places water can come from
- and aquifer
- reservoir
- lakes and rivers
What are the 3 stages of water purification and what do they do?
- Sedimentation - removes karate suspended particles
- Filtration - removes small suspended particles
- Chlorination - kills microbes on the water
What is a problem with purification?
Some soluble products are not removed. Some of which can be poisonous
Very pure water can be produced through distillation. But what is a problem with distillation?
It takes a lot of energy to do it and so it is usually too expensive to make large amounts of water this way
What solution is used to test for sulfate ions in water?
Barium chloride solution
To test for sulfate ions in water, barium chloride is added to a test tube full of water. What happens to the water if there are sulfate ions present?
A white precipitate of barium sulfate forms
What other substance forms other than barium sulfate when you react sodium sulfate with barium chloride?
Sodium chloride
Which solution is used to test for halide ions?
Silver nitrate solution
What colour does the precipitate go if each of these ions are present in water (separately):
- chloride
- bromide
- iodine
Chlorine - white precipitate
Bromine - cream precipitate
Iodide- yellow precipitate
