UNITS 2&12- ATOMIC STRUCTURE

Essential ideas:

The mass of an atom is concentrated in its minute, positively charged nucleus.
The quantized nature of energy transitions is related to the energy states of electrons in atoms and molecules. (HL)

Atoms are made of tonnes of teeny little particles called quarks and stuff. Thankfully, as chemists, we don’t have to worry about these really annoying particles – we just have to keep track of protons, neutrons, and electrons. We’ll let the physicists keep the weirdos and we'll just concentrate on the main players.

In this unit, you will delve into the components of atoms and how their constituent properties affect their reactions.

Syllabus for unit

Protons, neutrons, and electrons

You should know that all molecules are made up of protons, neutrons and electrons.

A brief overview:

Protons have a charge of +1 and are in the nucleus of atoms. They have a mass of about 1 atomic mass unit (amu).
Neutrons have no charge and are in the nucleus of atoms. They also have a mass of about 1 amu. Their purpose is to separate the protons so that the repulsion between them doesn’t blow the nucleus apart.
Electrons have a charge of -1 and live in the orbitals of the atom, outside of the nucleus. The mass of an electron is so small (about 1/1836 that of a proton) that it’s generally just treated as zero. It is the transfer and sharing of electrons between atoms that is responsible for chemical reactions.

Electrons and orbitals:

What electrons and orbitals are not:

Electrons are not little particles that move around the atom. They’re said to exist in orbitals, but they don’t actually orbit anything. So quit pretending that they circle the nucleus in some fashion!
Electrons and orbitals don’t look anything like a basketball. Though you may see pictures in which orbitals look like 3-D shapes, they’re just shorthand ways of showing you what orbitals look like. For this reason, don’t think that a 1s orbital looks like the surface of a basketball.
Electrons are not little particles that jump around the atom.

What electrons are:

Electrons are three-dimensional standing waves.

In an atom, electrons are not particles of negative charge, but 3-dimensional waves with negative charge.
Electrons are usually referred to as “electron clouds” as a way of helping people understand what they are, but they’re not clouds at all. The term “cloud” makes it sound like an electron is just loafing around occupying space. In real life, an electron is a stable, three dimensional standing wave.
Orbitals are the potential areas where electrons can live.
Electrons and orbitals aren’t the same thing.