Topic 1 - Key Concepts in Chemistry

Describe the history of the creation of the atom theory

 In 1803, Dalton created a solid atom model, where all atoms of an element were identical, but different elements had different atoms. However, in 1897, Thomas discovered the electron, and consequently in 1904, discovered the plum pudding model, which was a positively charged sphere, with negative electrons inside. In 1911, Rutherford suggested that atoms have a positive nucleus surrounded by orbiting electrons, and in 1913, Bohr discovered the electron shell model we use today. The proton and neutron were discovered in 1918 and 1932 respectively.

What is the charge and mass of:

Protons?

Neutrons?

Electrons?

P - charge of +1, mass of 1

N - charge of 0, mass of 1

E - charge of -1, mass of 1/1836

What is the mass number and what is the atomic number

Mass number refers to total number of protons and neutrons

Atomic number refers to the number of protons in an element

Atoms always have the same atomic number

Define Isotope

Same number of protons but different number of neutrons. They have the same chemical properties

How can relative atomic mass not be a whole number

it is a weighted average of all the isotopes

Relative Atomic Mass formula

mass 1 x abundance 1 + mass 2 x abundance 2 / 100

Periodic Table History

Mendeleev created the periodic table. He ordered elements in order of their relative atomic mass. He then checked their properties and swapped some elements so that similar properties lined up. He left gaps where he thought there would be other elements.

How come Mendeleev was able to predict new elements

He left gaps, and could decipher the properties of elements which fit in these gaps

How is the current periodic table laid out

In the current periodic table, the horizontal rows are periods, and the vertical collum are called groups. Elements with similar properties are placed in groups. Periods are arranged in increasing atomic number.

Where are metals on the periodic table

left and centre, due to metals having up to two electrons in their outer shell

How does electronic configuration relate to position on periodic table

The number of shells is equivalent to the period number, the number of outer shell electrons is equivalent to the group number, and the total number of electrons is equivalent to the atomic number.

When are ionic compounds formed

metal + non metal, when electrons are transferred to create a charged particle

When do you use -ide and when do you use -ate

-ide refers to anions formed from single non-metal ions

-ate refers to anions formed from three or more elements (one of which is oxygen)

Structure and bonding of ionic compounds

Strong electrostatic forces between oppositely charged ions. Regular lattice structure.

What is a covalent bond

pair of electrons shared between two non-metal atoms

Size of atoms and molecules

0.1 nanometre

Physical properties of ions

high melting and boiling points, soluble in water, cannot conduct electricity when solid, but can when aqueous

Structure and bonding of simple covalent structures

weak intermolecular forces between molecules which are joined together by strong covalent bonds

Physical properties of simple covalent structures

low melting and boiling points, insoluble, cannot conduct electricity

Structure and Bonding of giant covalent structures

arranged in a regular lattice structure, joined together by strong covalent bonds

physical properties of giant covalent structures

high melting and boiling points, insoluble, cannot conduct electricity

Structure and Use of Diamond

each atom makes four bonds, and is used in cutting tools as the rigid lattice structrue and strong bonds make it very hard

Structue and use of graphite

each atom forms three bonds, and there are strong covalent bonds between atoms. often used as lubricant as layers are able to slide over each other. also can be used as an electrolyte, as contains delocalised electrons

structure and use of graphene

single layer of graphite, can conduct electricity and is very strong. can be rolled into balls or nanotubes

structrue and bonding of metals

giant lattice of positively charged ions surrounded by a sea of delocalised electrons. strong electrostatic forces of attraction between positive metal ions and delocalised electrons

physical properties of metals

high melting and boiling points, insoluble, very good conductors of electricity

Properties of metals

solid, with high melting and boiling points, shiny when polished, malleable and good conductors of electricity

how does a non-enclosed system impact a reaction

 reactive non metals mass will increase as oxygen atoms combine to create metal oxide. Reactive non-metals decrease because products are heated and escape into air. Mass of a metal carbonate decreases if heated as carbon dioxide is produced which escapes.

how much is one mol

6.02×10²³

how does the limiting reactant control a reaction

the limiting reactant is the reactant which runs out first, and it controls how much product can be made