Unit 1 Flashcards
What is an atom?
the smallest particle of matter. Made up of electrons, protons, and neutrons
Who was Democritus?
he was the man who first suggested the idea of atoms in cells
What were the ideas of Democritus about atoms?
He thought that atoms were indivisible and he thought that they were indestructible
Who was John Dalton?
Dalton was a school teacher who took the ideas of Democritus and he performed experiments to research
What are the tenets of Dalton’s theory?
- All elements are composed of tiny indivisible particles called atoms
- Atoms of the same element are identical
- Atoms can combine in whole number ratios to form compounds
- Chemical reactions occur when atoms are separated, moved, or joined together
How small are atoms?
Atoms are in the range of
5 x 10^-11m to 2 x 10^-10m
What are the particles in the nucleus?
Proton neutron
Define atomic number
The number an atom is classified by based on the number of protons in said atom
define mass number
The mass of an atom ( add protons and neurons together)
What is an isotope?
An atom with the same number of protons but a different number of neutrons
what is atomic mass
The weighted average mass of the atoms in a naturally occurring sample element
How do you find atomic mass?
- Multiply the mass of each isotope by its natural abundance
- Add the products and the sum is your answer
Who discovered Electrons?
JJ Thompson
Who quantified the charge of an electron?
Robert Milikan
Who discovered the Proton?
Eugen Goldstien
