Parts of the Atom
Particle with a positive charge
Proton
Number of protons in an atom
Atomic number
Scientist who proposed the solid sphere model
John Dalton
Atoms of the same element with different numbers of neutrons
Isotopes
Sublevel that holds a maximum of 2 electrons
s
Particle found in the nucleus with no charge
Neutron
Atomic number of oxygen
8
Scientist who discovered the electron
J.J. Thomson
What stays the same in isotopes of the same element
Number of protons
Sublevel that holds 6 electrons
p
Region of the atom where protons and neutrons are located
Nucleus
Sum of protons and neutrons
Mass number
Name of Thomson’s model
Plum pudding model
Why atomic weight is usually a decimal
Because it is a weighted average of isotopes
Rule that states electrons fill lowest energy orbitals first
Aufbau principle
Two particles that have almost the same mass
Proton and neutron
Number of neutrons in Sodium-23 (Atomic # = 11)
12 neutrons
Experiment that led to the discovery of the nucleus
Gold foil experiment
Which is heavier: Carbon-12 or Carbon-14
Carbon-14
Electron configuration of oxygen
1s² 2s² 2p⁴
Subatomic particle whose mass is so small it is considered negligible
Electron
An atom has 16 protons and a mass number of 34. How many neutrons does it have?
18 neutrons
Model that first introduced electrons in fixed energy levels
Bohr model
Calculate atomic weight:
X-10 (70%), X-12 (30%)
(10 × 0.70) + (12 × 0.30) = 7 + 3.6 = 10.6
Noble gas configuration for sodium
[Ne] 3s¹