| Name three signs of a chemical change | One or more new chemical are formed
Energy is taken in or given out, during the reaction
The change is usually difficult to reserve |
| What are the forces that bonds ionic compounds called? | Electrostatic force |
| Describe the structure of an ionic compound. | They form a giant lattice structure which is a regular pattern containing a very large number of alternating positive ions and negative ions . |
| Give three properties of ionic compounds | Ionic compounds have high melting and boiling points
Ionic compounds are usually soluble in water
Ionic compounds conduct electricity when melted/dissolved in water |
| Why can ionic compounds conduct electricity when melted/dissolved in water? | When ionic compounds are dissolved in water or melted, their ions become free to move therefore are able to conduct electricity |
| Why do ionic compounds have high melting and boiling point? | Since ionic bonds are very strong lots of heat energy to break up the lattice. |
| Why does magnesium oxide have a higher melting sodium chloride? | This is because magnesium and oxygen ions have double the charges of sodium and chlorine ions. |
| Give three properties of covalent bonds | Covalent compounds have low melting and boiling point and many covalent liquids are volatile.
Covalent compounds tend to be insoluble in water
Covalent compounds do not conduct electricity |
| Give two examples of macromolecules | Diamond
Silicon (IV) Oxide |
| Why are diamonds so strong and have high melting points? | Since each atom is held in place by 4 strong covalent bonds |
| What are allotropes? | Different form of an element. |
| Give two differences between graphite and diamond | Diamonds are hard but graphite is soft and slippery
Diamonds can't conduct electricity but graphite can |
| Why is graphite able to conduct electricity? | Since they form only three bonds, the fourth electron is free to move carrying a charge |
| Give three properties and two uses of diamond | Properties
-Hardest known substance
-Can not conduct electricity
-Shiny when cut
Uses
-Used for cutting
-Used for jewellery |
| Give three properties and three uses of graphite | Properties
-Soft and slippery
-Soft and dark in color
-Conducts electricity
Uses
-Lubricant
-Pencil lead
-Electrodes |
| Give three properties and three uses of silicon (IV) oxide | Properties
-Hard
-Lets light through
-High melting point
Uses
-Sandpaper
-Glasses and lenses
-Bricks for lining surfaces |
| What is a metallic bond? | A bond formed through the attraction between metal ions and electrons |
| Give four properties of metallic bonds and explain the reasons for those properties | Metals USUALLY have high melting points since lots of energy is required to break its strong metallic bonds
Metals are malleable and ductile since layers of the metallic bonds can slide past each other without breaking the bond since electrons are free to move too
Metals are good conductors of heat as free electrons take in heat energy and quickly transfer throughout the metal structure
Metals are good conductors of heat since the free electrons can move through the lattice |
