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