Atomic Structure & Periodic Table – One Page Study Guide ⸻ Atomic Scientists (In Order) Democritus – matter made of indivisible particles (atomos) Dalton – modern atomic theory; atoms combine in whole-number ratios J.J

Atomic Scientists (In Order)

Democritus – matter made of indivisible particles (atomos)

John Dalton – modern atomic theory; atoms combine in whole-number ratios

J.J. Thomson – discovered the electron; plum pudding model

Ernest Rutherford – discovered the nucleus; atom mostly empty space

Neils Bohr – electrons in fixed energy levels

James Chadwick- discovery of neutrons

Werner Heisenberg- uncertainty principle

Periodic Table: Element Types & Location

Metals – shiny, conductive, lose electrons

Nonmetals – dull, brittle, gain electrons

Metalloids – mixed properties

Ions & Isotopes

Ion – charged atom

• Cation: positive (lost electrons)

• Anion: negative (gained electrons)

Isotopes

• Same protons

• Different neutrons

• Different mass

Periodic Table Groups

Group Name

#

Alkali Metals

1

Alkaline Earth Metals

2

Transition Metals

3-12

Boron Group

13

Carbon Group

14

Nitrogen Group

15

Oxygen Group

16

Halogens

17

Noble Gases

18

Total Electrons = atomic number (neutral atoms)

Valence Electrons =

• Outer shell electrons

• Control reactivity