Unit 2: Atoms and Molecules Flashcards
basic particle of chemical elements
atom
consists of a nucleus protons and neutrons, surrounded by an
electromagnetically-bound swarm of electrons.
atom
nucleus is made up of
proton + neutron
subatomic particles of an atom
protons
neutrons
electrons
atomic model and theory timeline
democritus
john dalton
jj thomson
ernest rutherford
niels bohr
erwin schrodinger
james chadwick
modern
- matter was made of small, hard particles called atoms (atomos)
- indivisible
- proposed that matter could not be divided into smaller pieces forever
democritus
- created the very first atomic theory known as the Billiard Bell
- viewed atoms as tiny, solid balls
- matter is made up of atoms
- elements are composed of subatomic atoms
- isotopes, isobars
- compounds are formed from 2 diff elementd
- atoms combine in somple ratios to form compounds
john dalton
- raisin bread model/plum pudding
- he showed that the atom was made of even smaller things
- discovered Electrons (with Cathode Ray Tube)
jj thomson
- discovered protons gold foil or alpha scattering experiment by using radium
- discovered protons and the nucleus
- he discovered that atoms have (+) particles in the center, and are mostly empty space
ernest rutherford
- planetary model
- nucleus is = to protons + neutrons
- nucleus is surrounded by electrons
- improved on rutherford’s model
- proposed that electrons move around the nucleus in specific layers, or shells
niels bohr
- quantum mechanical model
- electron cloud model
- estimates the probability of finding an electron in a certain
position
erwin schrodinger
- discovered neturons
- working with rutherford, he discovered particles with no charge, these were called as neutrons
james chadwick
- work done since 1920 has changed the model
- the new atomic model has electrons moving around the nucleus in a cloud
modern
atomic #
protons = electrons
mass #
electrons + neutrons
protons + neutrons
neutrons
mass # - electrons
mass # - atomic #
- same atomic # but different mass #
- same no. of protons
- H, protium, deuterium, tritium
H1, H2, H3
isotope
- same mass # but different elements
calcium (40) and argon (40)
isobar
- same # of neutrons
- different elements
carbon 13
nitrogen 14
isotones
determines the charge number of an atom, it also tells us the number of electrons in a neutral atom
atomic number
The sum of the number of protons and neutrons in an atom (whole number)
mass number
The ________ number of protons and neutrons for all natural _________ of an element (decimal number)
atomic mass/weight
