Science 3rd Q

John Dalton

Proposed the Solid Sphere model of atomic theory.

J.J. Thomson

Created the Plum Pudding model and discovered electrons.

Ernest Rutherford

Developed the Nuclear Model of the atom.

Niels Bohr

Introduced the Planetary Model of the atom.

Erwin Schrodinger

Developed the Quantum Model of the atom.

Atomic Number

Equals the number of protons and electrons in an atom.

Atomic Mass

Equals the number of protons plus neutrons.

Isotopes

Atoms of the same element with different numbers of neutrons.

Periodic Law

States that atomic number is more important than atomic mass.

Metalloids

Elements that have properties between metals and non-metals.

Alkali Metals

Group 1A; the most reactive metals.

Halogens

Group 7A; highly reactive non-metals, with Fluorine being the most reactive.

Noble Gases

Group 8A; the most stable group of elements.

Atomic Size Trend

Decreases from left to right and increases from top to bottom on the periodic table.

Ionization Energy Trend

Increases from left to right and decreases from top to bottom.

Valence Electrons

Number of electrons in the outermost shell of an atom.

Octet Rule

States that atoms are stable with 8 valence electrons.

Anions

Negatively charged ions formed by gaining electrons.

Cations

Positively charged ions formed by losing electrons.

Ionic Bonding

A bond formed between a metal and a non-metal through the transfer of electrons.

Covalent Bonding

A bond formed between two non-metals through the sharing of electrons.

Lewis Dot Structure

A representation of valence electrons as dots around an element symbol.

Electron Configuration

The distribution of electrons among the energy levels of an atom.