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
anhydrous salt
the product that remains after heating the hydrate and the water evaporates
molecular formula
exact number of atoms of each element in the compound
empirical formula
simplest whole number ratio of a compound
