atomic structure + chem-math Flashcards
atom
the smallest particle of an element.
nucleon
any particle found in the nucleus (protons & neutrons)
atomic number (nuclear charge)
number of protons
- all atoms of the same element have the same number of protons
protons
- particles found in nucleus
- mass = 1 atomic mass unit (amu)
- charge = +1
neutrons
- particles located in nucleus
- mass = 1 amu
- slightly bigger than protons
- neutral charge
- # neutrons = mass number - # protons
electron
- particles that revolve / rotate around the nucleus
- very small
- mass = 1/1835 of a proton **almost 0 amu
- charge = -1
- all atoms are neutral; # electrons = # protons
- gained or lost in chemical reactions
ions
atoms with a charge
- # protons ≠ # electrons
- amt of positive charge ≠ amt of negative charge
atoms vs ions
1) atoms that lose electrons (metals) become positively charged.
- lost negative charge
2) atoms that gain electrons (nonmetals) become negatively charged
- gained negative charge
mass number
neutrons + # protons
isotopes
atoms if the same element that the same number of protons, BUT a different number of neutrons
atomic mass
the average (by percent) of the masses of all naturally occurring isotopes of an element
history of the atom
john dalton (cannonball model)
- atoms were solid with indivisible (unbreakable) parts
- believed atoms are the basic unit of matter
history of the atom
j.j. thompson (plum pudding model)
- discovered electrons using a cathode ray tube
- believed atoms were solid. positive spheres with electrons embedded in it
history of the atom
ernest rutherford (nuclear model)
- an atom has a positive nucleus at the center with electrons outside the nucleus
- atom is mostly made up mostly of empty space
observations:
1. most alpha particles went through gold foil
2. occasionally an alpha particle was deflected back
conclusion:
1. atoms is made up of mostly empty space
2. an atom has a positive, dense, nucleus
history of the atom
niels bohr (planetary model)
- electrons are arranged in energy levels in orbit
- know the bohr diagram – with rings/pels, # electrons in each pel (configuration)
orbitals
- electrons are found in orbitals
- area of electron probability
electron configuration
electrons in each ring around the atom
last number (ex: Al: 2-8-3**) = # valence electrons
valence electrons
-electrons located in the outermost ring of an atom (usually involved in bonding)
ground state
- all the electrons are in the lowest energy orbitals/rings
- ex: phosphorus 2-8-5 –– # electrons in each ring
excited state
- an electron has absorbed energy and temporarily moved to a higher energy ring
- unstable condition
- one electron jumped from the second ring to the third ring
- ex: phosphorus (excited) 2-7-6
how different colors are produced:
- when an electron(s) absorbs energy, it jumps away from the nucleus and enter the excited state
- when the electron falls back down to the ground state, it releases energy in the form of light
mole
- represents a number
- 1 mole = 6.02 x 10^23 (avogadro’s number)
ex: 1 mol of atoms = 6.02 x 10^23 atoms
- 1 mole = 6.02 x 10^23 (avogadro’s number)
gram formula mass (gfm)
mass of 1 mole of a substance
- watch for diatomics
- H2, O2, N2, Cl2, Br2, I2, F2
hydrate
a salk that has adefinite amt of water molecules embedded into its structure
