Atomic Structure - Chemistry

Proton

A subatomic particle with a relative mass of 1 and a relative charge of +1, found in the nucleus.

Neutron

A subatomic particle with a relative mass of 1 and a relative charge of 0, located in the nucleus.

Electron

A subatomic particle with a relative mass of 1/2000 and a relative charge of -1, orbiting the nucleus.

Relative atomic mass

The average number of protons and neutrons in an element, shown above element on periodic table

Atomic number

The number of protons in an atom of an element, unique to each element., below element on periodic table

Number of neutrons

mass number - atomic number.

The atom is neutral.

The number of electrons is equal to the number of protons in a neutral atom.

Radius of an atom

Approximately 0.1 nm (1 x 10^-9 m).

Nucleus

The small core of an atom made of positive protons and neutral neutrons.

Element

A substance made from one type of atom, found on the periodic table.

Compound

A substance formed from two or more different atoms chemically bonded together.

Mixture

A combination of two or more elements and/or compounds not chemically bonded together.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons. Isotopes have nearly identical chemical properties but different physical properties.

Energy levels

The layers outside the nucleus where electrons occupy different shells.

First shell capacity

Holds a maximum of 2 electrons.

Second shell capacity

Holds a maximum of 8 electrons.

Third shell capacity

Holds a maximum of 8 electrons.

Fourth shell capacity

Holds a maximum of 2 electrons.

Group number

Corresponds to the number of outer shell electrons an element has.

Noble gases

Elements in group 8/0 with full outer shells, making them stable and unreactive.

Scientific model

A simplified system that helps understand a more complex system.

Democritus's theory (500 BC)

Proposed atoms are small, invisible, indivisible, and indestructible particles with empty space in between them.

Plum pudding model (1897)

J.J. Thomson's model suggesting electrons are embedded in a positive 'batter'.

Rutherford's experiment (1911)

shot positive alpha particles at leaf, expected all of them to go through; most went through, some reflected and deflected; theorised atoms mostly empty space, but positive thing in middle present

Bohr model (1911-1932)

Proposed that electrons revolve around the nucleus in stable orbits (shells).; further experiment led to idea that positive charge in nucleus due to tiny particles called protons

James Chadwick (1932)

Discovered the neutron, a new particle in the nucleus.

Chemical bonding

Involves losing or sharing electrons from outer shells to achieve noble gas electronic structure.

Something made of ions.

Compounds formed from metals and non metals made of ions.

Electron transfer

Metals lose electrons to form positive ions

Non-metals gain electrons to form negative ions

Ionic bonding

Occurs when a metal bonds with a non-metal, involving the transfer of electrons.

Ionic compounds

Structures held together by strong electrostatic forces between oppositely charged ions.

Lattice structure

The repeating arrangement of positive and negative ions extending in all directions.

High melting and boiling points - ionic compounds

Ionic compounds require large amounts of energy to break strong bonds.

Conduct electricity - ionic compounds

Ionic compounds in liquid form can conduct electricity, allowing ions to move and carry charge.

Covalent bonding

Occurs when two non-metals bond by sharing electrons.

Metallic structure

Contains repeating patterns of positive metal ions and delocalised electrons.

Metallic bond

The electrostatic attraction between positive metal ions and delocalised electrons, free to move throughout whole structure

High melting and boiling points - metals

Require large amounts of energy to overcome strong electrostatic forces.

Good electrical conductors - metals

Delocalised electrons in metals can move and carry electrical charge.

Good thermal conductors - metals

Thermal energy is transferred by delocalised electrons in metals.

Malleable metals

all ions same size, form layers, can slip & slide over each other while maintaining metallic bonding.

Sonorous metals

Produce sound when struck.

Delocalised electrons

Electrons which can move freely throughout the metal.

Periodic table

A chart organizing all known elements based on their atomic structure.

Chemical bonding types

ionic bonding, covalent bonding, and metallic bonding.