Chemistry Chapter 1: Atomic Structure

 CHEMISTRY KEYWORDS:

Element: A substance containing only one type of atom. All the atoms in an element have the same proton number.

Compounds: Most elements are found in combination with other elements.

Atom: The smallest part of an element that can take part in a chemical change. Every atom contains protons in its nucleus and electrons outside the nucleus. Most atoms have neutrons in the nucleus.

Nucleus: Every atom has nearly all of its mass concentrated in a tiny region in the centre of the atom.

Nucleons: The nucleus is made up of particles.

Proton: Positively charged particle in the nucleus of the atom.

Neutron: Uncharged particle in the nucleus of an atom, with the same relative mass as proton.

Electron: Negatively charged particles found in orbitals outside the nucleus of an atom. It has negligible mass compared with a proton.

Orbitals: Outside the nucleus, electrons move around in regions of space.

Energy levels: The specific distances from the nucleus corresponding to the energy of the electrons. Electrons in energy levels further from the nucleus have more energy than those closer to the nucleus. Energy levels are split into sub-levels, which are named s, p, d, etc.

Anode: The positive electrode (where oxidation reactions occur).

Mass number: The number of protons + neutrons in an atom. Also called the nucleon number.

Radioisotopes: Radioactive isotopes

Ions: Charged particles formed by the loss or gain of electrons from an atom or group of covalently bonded atoms.

CHEMISTRY DEFINITIONS:

Atomic Number: The number of protons in the nucleus of an atom. Also called the proton number.

Isotope: Atoms of the same element with different mass numbers.

CHEMISTRY IMPORTANT NOTES:

Subatomic Particle	Symbol	Relative Mass	Relative Charge
Electron	e	1/1836	-1
Neutron	n	1	0
Proton	p	1	+1

 

SUMMARY:

Beams of protons and electrons are deflected by electric fields but neutrons are not.

The atom consists of positively charged protons and neutral neutrons in the nucleus, surrounded by negatively charged electrons arranged in energy levels (shells).

Isotopes are atoms with the same atomic number but different mass numbers. They only differ in number of neutrons they contain.