Structure of the Atom

Electron

a negatively charged particle found in the electron cloud has almost no mass

Neutron

a neutral particle (no charge) found in the nucleus has the mass of 1

Proton

a positively charged particle found in the nucleus has the mass of 1

Dalton's Theory

all matter is made up of individual particles called atoms which cannot be divided. no subatomic particles. all elements are composed of atoms. compounds contain more than 1 element.

planetary model

the nucleus isnsurrounded by a large volume of empty space (nuclear model). electrons are placed in specific energy levels outside the nucleus. electrons move around the nucleus like planets move around the sun.

nuclear model

the positive charge of an atom is concentrated in a very small, dense, central area called the nucleus (contains protons). atoms now have electrons and protons. atom is mostly empty space.

Mass Number

the sum of the number of neutrons and protons in an atomic nucleus

Atom

the tiny particles that make up everything

Isotope

Atoms of the same element that have different numbers of neutrons

Atomic Number

Number of protons in an atom

Nucleus

The central core of an atom

Energy Level

1st level - 2 2nd level - 8 3rd level - 8

Electron Cloud

A region around the nucleus of an atom where electrons are found mainly empty space which has almost no mass

Orbital

A region in an atom where you would find electrons*

electron cloud model

electrons move in a less predictable manner. electrons move very fast around the nucleus in orbitals (regions), creating a blurry sphere or cloud. the nucleus now has protons, neutrons. neutrons help stabalize the nucleus.

Plum Pudding Theory

negatively charged particles were discovered. first evidence of subatomic particles. electrons are evenly scattered throughout a sphere of positive charge. all atoms are neutral (no charge). negative electrons balance the positive sphere.