Bonding and Calculations Flashcards
(21 cards)
What does the mass number represent?
Total number of protons and neutrons.
What does the atomic number represent?
Number of protons
What is a compound?
Compounds are formed when atoms of two or more elements are chemically combined together.
Define the term isotope?
Isotopes are different atomic forms of the same element, which have the same number of protons but a different number of neutrons.
Describe the process of ionic bonding?
In ionic bonding, atoms lose or gain electrons to form charged particles (called ions) which are then strongly attracted to one another ( because I there attraction of opposite charges)
List the main properties of ionic compounds?
Have giant iconic structures
High melting points & boiling points due to strong attraction.
When ionic compounds melt the ions are free to move and they’ll carry an electrical current
Dissolve easily in water.
What type of of ion do elements from group 1 form?
They are metal so they lose electrons to form positive ions.
What type of ion do elements from groups 7 form?
They are non-metal. They gain electrons to form negative ions.
What is covalent bonding?
Covalent bonding is where atoms share electrons with each other so that they’ve got a full outer shells.
What are the two types of covalent substances? Give three examples of each.
Simple molecular- chlorine
Oxygen
Water
Giant Covalent structures-
Diamond
Silicon dioxide
Graphite
Give an example of a “smart” material and describe how it behaves?
Nitinol “shape memory alloy” it’s a metal alloy, around half nickel half titanium but when it’s cool you can bend it and twist it like rubber. If you bend it too far and it stays bent you can just heat it above a certain temperature and it does back to its remembered shape.
Used in glasses frames and braces.
What are nanoparticles?
Nanoparticles are tiny particles 1-1000 nanometers across, they roughly contain a few hundred atoms.
Name two applications of nanoparticles?
Used to make sensors to detect one type of molecule, testing the purity of water.
Nanotubes can be used to make stronger lighter building material
Sunscreen and deodorant, small particles do the job without leaving a white stain on the skin.
Nanotubes conduct electricity so they can be used in tiny electrical circuits for computer chips
Explain the difference between thermosoftening and thermosetting polymers.
Thermosoftening polymers don’t have cross links between chains, meaning the forces between chains are really easy to overcome so it’s easy to melt. You can melt and reshape this plastic as many times as you like. Thermosetting polymers have crosslinks meaning the polymer doesn’t soften when heated, they are strong hard and rigid.
Define relative atomic mass and relative formula mass?
How heavy different atoms are compared with the mass of an atom.
What is the link between moles and relative formula mass?
The relative formula mass of a substance in grams is known as one mole of the substance.
What is an empirical formula?
Way of finding out the formula of a compound.
Describe three factors that can reduce the percentage yield of a reaction?
Some products are always reacting together to change back to the original reactants.
When you filter a liquid to remove a solid. Some product may be lost then it’s separateness from the reaction mixture.
Sometimes there fan be unexpected reactions happening which use Ik the reactants.
Explain how chromatography can be used to analyse the dyes used in a brown sweet?
Extract the colour from the food sample by placing it in a small cup with a few drops of solvents.
Put spots of the solution on a pencil baseline on filter paper.
Roll up the sheet and put it in a beaker with some solvent. The solvent will seep up the paper taking dyes with it.
Briefly describe how gas chromatography works?
A gass is used to carry substances through a column packed with a solid material. Substances travel at different speeds and so are separated. The time taken to reach the detector is called a retention time. It’s used to identity substances
How do you work out the number of electrons?
Subtract the atomic number (bottom) from the mass number (top).
