No overall charge because there are equal numbers of postive protons and negative electrons.
Atomic number is the smaller number.
Mass number is always the bigger of the two - massive mass number.
Number of neutrons = mass - atomic number
He = 4 - 2 = 2 neutrons.
Inner ring can have 2 electrons,
Further outer rings can have up to eight.
Has 2 electrons in inner ring, then 6 on the outer ring.
Note to readers: The alkali metal and halogens card leads on from this one.
Alkali metals and halogens.
ALKALI METALS AND HALOGENS!
+ 1 electron in their outer shell
+ react with a non-metal element to form ionic compounds with a postive charge. (+)
+ 7 electrons in their outer shell
+ react with an alkali metal to from ionic compounds.
Mixtures and compounds:
Mixtures - two or more elements that are not chemically combined.
Compounds - two or more elements that are chemically combined.
Ionic bonding and covalent bonding.
IONIC BONDING & COVALENT BONDING!
- high melting and boiling points.
- strong bonds therefore conduct electricity.
- between a postive and negative.
+metal and non-metal.
- transfer of electrons (e-)
-atoms become postive if they loose e-.
-atoms become negative if they gain e-.
- between two non-metals
- dot and cross diagrams
- strong bonds formed when e- shared.
- sharing of electrons.
- very strong bonds therefore very high melting point.
- metals, layers can be bent and shaped.
+ lattice structure
+ each carbon atom forms 4 bonds.
+ lots of bonds, very strong and hard.
+ not easily shaped.
+ only form 3 bonds.
+ layered structure
+ form of carbon
+ 1 electron is delocalised so graphite can conduct electricity and heat.
+ layers can slide past each other - soft and slippery.