Number of Protons
Number of Protons + Neutrons
Left Superscript = mass number6
Left Subscript = atomic number6
3535Atomic Number = ?
2010Mass Number = ?
2713Mass Number = ?
2020Atomic Number = ?
Atoms of the same element with a different # of neutrons
Characteristics of Proton
Charge = +1, mass = 1 amu, location = inside nucleus
Characteristics of Neutron
Charge = 0, mass = 1 amu, location = inside nucleus
Characteristics of Electron
Charge = -1, mass = 1/1836 amu or 0.0005 amu, location = outside nucleus
An atom that has gained or lost electrons & so carries charge
Protons & Neutrons
Smallest bit of an element that retains the properties of the element.
Electrically neutral. # of protons = # of electrons.
# protons - # electrons
# of neutrons
Mass number atomic number
86# of neutrons = ?
54# of neutrons = ?
2218# of neutrons = ?
87# of neutrons = ?
Right superscript = charge122+
10 electrons122+# of electrons?
36 electrons371+# of electrons?
53 electrons521-# of electrons?
18 electrons162-# of electrons?
Positive ion: atom lost electrons
Negative ion: atom gained electrons
Avg. Atomic Mass
Weighted avg. of masses of naturally occurring isotopes of an element.
2 isotopes of Cl: 75% Cl-35 & 25% Cl-37.Calculate avg. atomic mass.Avg. atomic mass = .75(35) + .25(37) = 35.5 amu
Billiard Ball Model
Plum Pudding Model-----+++++
Rutherfords ExperimentSource: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic
Rutherfords Experiment: ResultsMost of the alpha particles went straight through. Most of the atom is empty space.
Some of the alpha particles were deflected back. The nucleus was tiny, but contained most of the mass of the atom.
Modern or Quantum Mechanical ModelSource: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic
Bohr ConfigurationGround state configurations found in reference tables.Cannot be predicted.
Bohr Configuration of Na = 2-8-12 electrons in energy level 18 electrons in energy level 21 electron in energy level 3
Bohr Diagram of Na+11
Bohr ModelElectrons are restricted to specific orbits or shells or principle energy levels.Each shell holds a specific # of electrons.Each shell has a specific energy & radius.Energy of electron must match energy of shell.
Maximum Capacity of Bohr Levels2818322n2
Ground StateBohr modelEvery electron is in the lowest available orbit.
Excited StateBohr modelAn electron has absorbed heat, light, or electrical energy and moved to a higher energy level.Unstable. Returns to ground state quickly by emitting a photon.
Continuous SpectrumSpectrum produced by holding a prism in sunlight. Contains light at every wavelength.
Bright Line SpectrumVisible light produced by electrons in atom returning to ground state: light of only a few wavelengths is present.
Each element has a unique bright line spectrum. Used to identify elements.
Wavelengths of bright lines correspond to difference between energy levels.Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic
Absorbtion of EnergyhGround stateExcited stateE1E2E3
Emission of EnergyhGround stateExcited stateE1E2E3
OrbitalModern ModelRegion of space that holds 2 electrons.Has a specific energy. Shapes vary.