Protons are positively charged particles found in the nucleus.
Neutrons have no charge, they are also located in the nucleus.
The nucleus is the centre of an atom
Electrons are negatively charged particles that orbit around the nucleus
The number of protons is equal to the atomic number
Atoms can gain or lose electrons to form ions.
The mass number is the total number of protons and neutrons in an atom
A universal indicator turned blue. What is the pH value of the solution?
9
Why are nanoparticles effective in very small quantities?
They have a higher surface area to volume ratio
Give one advantage of using nanoparticles in sun creams.
Better Coverage
Give one disadvantage of using nanoparticles in sun creams.
Potential cell damage
Suggest two reasons why 9 carat gold is often used instead of pure gold to make jewellery.
9 carat is cheaper
24 carat is soft
Propane (C3H8) is used as a fuel. Complete the equation for the complete combustion of propane. C3H8 + 5O2 → 3 .............................. + 4 .................................
(3) CO2
(4) H2O
Water from a lake in the UK is used to produce drinking water.What are the two main steps used to treat water from lakes?
filtration by passing through filter beds to remove solids
sterilisation to kill microbes
Explain why it is more difficult to produce drinking water from waste water than from water in lakes.
water needs more as it contains more microbes
Why is producing drinking water from sea water expensive?
High energy requirement
Explain how a covalent bond holds two atoms together.
electrostatic force of attraction between shared pair of negatively charged electrons and both positively charged nuclei
Explain, in terms of particles, how and why the rate of reaction changes during the reaction of calcium carbonate with hydrochloric acid.
acid particles used up so concentration decreases so less frequent collisions so rate decreases
Explain how increasing the pressure of the reactants will affect the amount of ethanol produced at equilibrium.
more ethanol will be produced because system moves to least
Describe, as fully as you can, what happens when magnesium atoms react with oxygen atoms to produce magnesium oxide.
Magnesium loses electrons and oxygen gains electrons. two electrons gives full outer shells
Silicon dioxide has a very high melting point. Other substances are added to silicon dioxide to make glass. Glass melts at a lower temperature than silicon dioxide. Suggest why
Weaker bond
Glass can be coloured using tiny particles of gold. Gold is a metal. Describe the structure of a metal.
Lattice of positive ions with delocalised electrons