All atoms of a particular element have an EQUAL number of protons and electrons; meaning atoms have no overall charge.
The ATOMIC NUMBER is the number of protons an atom has.
The ATOMIC NUMBER is how the Periodic Table is arranged.
The first shell can only contain a maximum of 2 electrons. The shells after can hold a maximum of 8 electrons.
Elements in the same group have the same amount of electrons in the outer-most shell.
The ATOMIC NUMBER shows how many electrons you have to write in the shells. (E.G. Sodium has an atomic number of 11 so its shells are filled 2,8,1)
Ionic Bonding occurs between a METAL and a NON-METAL.
Ionic Bonding is the transfer of electrons from on atom to the other to form electrically charged ions, each which has a full outer shell.
When an atom LOSES electrons then it becomes POSITIVELY charged.
So when an atom GAINS electrons then it becomes NEGATIVELY charged.
Ionic Compounds are GIANT structured of ions held together by strong forces of attraction between oppositely charged ions.
Ionic Compounds have HIGH MELTING POINTS and BOILING POINTS.
When an atom looses an electron it becomes NA+, if it gains an electron it becomes Na- .
The Covalent Bond is a very strong bond which is formed when electrons are SHARED.
E.G. a Chlorine atom has 7 electrons in its outer shell. Too be able to bond with another chlorine atom each atom shares 1 electron so each atom has 8 electrons in its outer-shell.
Atoms which share electrons, or Covalently Bond often form strong bonds in molecule form (e.g. H2)
Molecules formed Covalently include.... H2, Cl2, H2O, HCl, CH4 and O2
The Molecules that are formed actually have weak attraction to other molecules, this means they usually have low melting and boiling points.
1) DIAMOND. Form of Carbon that has a giant, rigid lattice where each carbon atom forms FOUR covalent bonds with other carbon atoms. The big number of covalent bonds makes diamond VERY HARD with a HIGH melting point.
2) GRAPHITE. In this form each carbon atom forms THREE covalent bonds with other carbon atoms in a LAYRED structure. The layers can slide past each other making Graphite SOFT and SLIPPY.
3) SILICON DIOXIDE. Silicon Dioxides lattice is similar to diamond's, where each oxygen atom is joined to TWO silicon atoms and each Silicon atom is joined to FOUR Oxygen atoms.
The MASS NUMBER is the TOTAL NUMBER of PROTONS and ELECTRONS.
The ATOMIC NUMBER is the NUMBER OF PROTONS
Number of Neutrons = Mass Number - Atomic Number
ISOTOPES... Some atoms of the same element can have different numbers of NEUTRONS, these are Isotopes. (HINT: They are easy to spot because they have the same atomic number but a different mass.
Relative Formula Mass is simply worked out by adding up all the Atomic mass numbers of all the elements in the compound.
E.G. H2O is (2x1)+16 = 18
(MASS OF ELEMENT IN COMPOUND ÷ MASS OF COMPOUND) x 100
The Empirical Formula of a compound is the simplest formula that represents what's in the compound, by mass.
E.G. 1) Find the mass of the elements in the compound. (2) Divide these masses by their Atomic masses... Fe = 1.12g ÷ 56 = 0.02. (3) Identify the ratio of atoms in the compound ... 0.02 x 100 = 2. This shows there must be a ratio of 2 Fe to every other element. Fe2 O3
A mole(mol) is a measure of the number of particles contained in a substance.
If a substance is an element the mass of one mole of that substance ,the molar mass(g/mol) is always equal to the atomic mass. E.G. Carbon is 12g/mol, Oxygen is 16 g/mol
If the substance is a compound add up all the elements atomic masses and represent it in grams. E.G. NaOH is 23+1+16 = 40g
Number of Moles of a Substance(g/mol) = Mass of Substance(g) ÷ Mass of one mole (g/mol)
Percentage Yield = (Yield from Reaction ÷ Maximum Theoretical Yield) x 100
Atom Economy is a measure of the amounts of reactants that end up as useful products.
Atom Economy = (Atomic Mass of Useful Products ÷ Atomic Mass of Reactants) x 100