| A | B |
|---|
| substance made of atoms which contain the same number of protons | element |
| Parts of an atom | protons & neutrons and electrons |
| Atomic number | number of protons in nucleus |
| Compound | made of two or more elements chemically joined together |
| mass number | total number of protons & neutrons |
| ions | atoms which have lost or gained electrons |
| ionic compounds | formed by transfer of elements between atoms of differnt elements |
| covalent molecules | atoms held together by shairing electrons |
| 2,8,8, | full shells ! |
| hydrocarbons | compounds of hydrogen and carbon only |
| alkanes | saturated hydrocarbons(single bond) |
| alkenes | unsaturated hydrocarbons( double bond) |
| cracking | breaking down large hydrocarbons into smaller molecules |
| acidic solution | pH less than 7 |
| alkaline solution | pH greater than 7 |
| neutral solution | pH equal to 7 |
| period | horizontal row of lements in periodic table |
| Group | vertical column of elements in periodic table |
| Alkali metals ( Li, Na, K) | Group 1 ( 1 electron in outer shell) |
| Noble gases | Group 0 ( full outer shell) |
| Exothermic | transfer heat to surroundings(feel warm) |
| Endothermic | transfer heat from surroundings ( feel cold) |
| Catalysts | speed up rate of a specific reaction |
