Scientists
Who believed matter contained indivisible particles?
Democritus
Who proposed the plum pudding model?
J.J. Thompson
Which particle is negative?
Electron
Atomic number equals the number of what?
Protons
A charged atom is called?
Ion
Who argued matter was continuous?
Aristotle
Rutherford developed what model?
Nuclear Model
Which particle is positive?
Proton
Mass Number = protons + what?
Neutrons
An atom gaining electrons becomes what?
Anion
Who proposed that elements consist of atoms?
John Dalton
Who placed electrons at specific energy levels?
Niels Bohr
Which particle has no charge?
Neutron
An atom has atomic #8 and mass #16. How many Neutrons?
8
An atom losing electrons becomes what?
Cation
Who discovered evidence for electrons?
J.J. Thompson
What model is currently accepted?
Quantum-mechanic Model
Where are protons and neutrons located?
Nucleus
Sodium-23 has atomic #11. Neutrons?
12
What makes isotopes of one element different?
Different numbers of neutrons
Whose experiment showed that positive charge and most mass were concentrated in the nucleus?
Rutherford
What are regions where electrons are likely to be found called?
Orbitals
Approximately how massive is an electron compared with a proton?
About 1/1836
An atom has 17 protons and 18 electrons. Charge?
-1
Why is atomic mass often a decimal?
It is a weighted average of naturally occurring isotopes