Chapter 2 - Atoms

structure of an atom

structure of an atom

Atomic structure refers to the structure of an atom comprising a nucleus (centre) in which the protons (positively charged) and neutrons (neutral) are present.

protons (mass, charge, location)

Protons have a positive electrical charge of one (+1) and a mass of 1 atomic mass unit (amu). Protons are found in the nucleus of the atom.

neutrons (mass, charge, location)

The neutron is a neutral particle found in the nucleus of an atom. Its relative mass is 1 u. It has no charge.

electrons (mass, charge, location)

mass of an electron is equal to the 0 amu. electrons are negatively charged. electrons revolve rapidly around the nucleus in fixed circular orbits called energy levels.

density of nucleus vs empty space

the density of an atom is similar to 6.2 billion cars in a 1 cubic foot box. between the nucleus and electrons is empty space

isotopes

Atoms with the same number of protons but different numbers of neutrons. They share almost the same chemical properties, but differ in mass and therefore in physical properties

atomic number

the number of a chemical element in the periodic system. Accordingly, the number of protons, which is always equal to the number of electrons in the neutral atom, is also the atomic number.

atomic mass

the quantity of matter contained in an atom of an element

scientists for quantum model

Niels Bohr and Max Planck each received a Nobel Prize in Physics for their work. Einstein is considered the third founder of Quantum Theory and won the 1921 Nobel Prize.

roygbiv and energy

Violet is the most energetic color and red is the least.

how atoms give off light

Atoms emit light when they are heated or excited at high energy levels. The color of light that is emitted by an atom depends on how much energy the electron releases as it moves down different energy levels.