Chemistry Basics

• the total number of protons and neutrons in an atom. Gives mass of element compared to Carbon 12

• the number of protons in the nucleus. By the default in a neutral atom, this is also the number of electrons

• atoms with the same number of protons but a different number of neutrons

• Radioactive tracers can be used to track atoms through metabolism.

• the electrostatic attraction between oppositely charged ions. The bond is formed between metals and non-metals. They form an ionic lattice - which are held together by electrostatic attractions between ions.

• a special type of dipole-dipole interaction. From when the hydrogen is covalently bound to a highly electronegative atom such as oxygen, nitrogen or fluorine. Hydrogen bonds form between different molecules.

• the sharing of a pair of electrons between two atoms. [H-H], [O=O], [O-H], [C-H]

• electrons are always moving. At any particular moment electrons may NOT be evenly distributed around the molecules. This creates a very temporary negative dipole. Larger masses or larger surface area increases boiling point because of increased area of van Der Waals forces.

• is the power of an atom within a molecule to attract the bonding electrons to itself.

• The relative atomic mass in grams of any elements contains one mole of atoms. 1 mole of C atoms = 12.01g of C atoms.

• The relative formula mass is the mass of 1 mole of a substance.
• The relative formula mass is calculated by adding together the atomic mass of each atom in the molecule.

   Amount In moles =                  Mass in grams       

                                             Mass of one mole (in grams)

   Molarity (M or mol/L) =             Moles (mol)       

                                                            Volume (L)

                                  C1 x V1 = C2 x V2

• C1 and C2 are the molarity of the concentration and dilute solutions, respectively
• V1 and V2  are the volume of the two solutions.

                                            (C x V (in L) = moles

Kc is a constant which shows the ratio of products to reactants at equilibrium.

• aA + bB <=> dD + eE

Kc =    [D]d[E]e     —> products

           [A]a[B]b     —> reactants

• If stress is applied to a system in dynamic equilibrium, the system will adjust to relieve that stress.
• Effect of changing pressure or volume: decrease volume, increased pressure (increase in pressure favours side with fewest moles. Equilibrium is shifted to the right). Increased volume, decreased pressure (decrease in pressure favours side with the most moles. Equilibrium shifted to the left).