Number of Protons Atomic Number

Number of Protons + Neutrons Mass Number

12 is the mass number. C-12 or carbon-12

Left Superscript = mass number 6

Left Subscript = atomic number 6

35 80Br 35 Atomic Number = ?

20 20Ne 10 Mass Number = ?

238 238U 92 Mass Number = ?

27 27Al 13 Mass Number = ?

20 40Ca 20 Atomic Number = ?

9 19F 9 Atomic Number = ?

Mass Number = 235 Atomic Number = 92 (Look up!)

Atomic Number = 6 (Look up!) Mass Number = 14 Atomic Number = 6 (Look up!) Number of neutrons = 14 - 6 = 8 C-14 How many neutrons?

Atoms of the same element with a different # of neutrons Isotope

Atoms with the same atomic # but different mass # Isotope

Characteristics of Proton Charge = +1, mass = 1 amu, location = inside nucleus Characteristics of Proton

Characteristics of Neutron Charge = 0, mass = 1 amu, location = inside nucleus Characteristics of Neutron

Characteristics of Electron Charge = -1, mass = 1/1836 amu or 0.0005 amu, location = outside nucleus Characteristics of Electron

An atom that has gained or lost electrons & so carries charge Ion

Protons & Neutrons Nucleons

Smallest bit of an element that retains the properties of the element. atom

Electrically neutral. # of protons = # of electrons. atom

# protons - # electrons Charge

Mass number – atomic number # of neutrons

8 14C 6 # of neutrons = ?

5 9Be 4 # of neutrons = ?

22 40Ar 18 # of neutrons = ?

8 15N 7 # of neutrons = ?

Right superscript = charge 24Mg 2+ 12

10 electrons 24Mg 2+ 12 # of electrons?

36 electrons 86Rb 1+ 37 # of electrons?

53 electrons 127Te 1- 52 # of electrons?

18 electrons 32S 2- 16 # of electrons?

9 protons, 11 neutrons, 10 electrons 20F - 9 # of protons, neutrons, electrons?

Positive ion: atom lost electrons Cation

Negative ion: atom gained electrons Anion

Weighted avg. of masses of naturally occurring isotopes of an element. Avg. Atomic Mass

2 isotopes of Cl: 75% Cl-35 & 25% Cl-37. Calculate avg. atomic mass. .75(35) + .25(37) = 35.5 amu 2 isotopes of Cl: 75% Cl-35 & 25% Cl-37. Calculate avg. atomic mass.

Billiard Ball Model Dalton’s Model

Plum Pudding Model Thomson’s Model + - - + - + + - + -

Nuclear Model Rutherford’s Model - - + -

Rutherford’s Experiment Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic

Rutherford’s Experiment: Results Most 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. Rutherford’s Experiment: Results

Planetary Model Bohr’s Model

Modern or Quantum Mechanical Model Schrodinger’s Model Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic

Modern Model (Schrodinger or Quantum Mechanical Model) Electron treated as a wave. Never know exactly where it is. Modern Model (Schrodinger or Quantum Mechanical Model)

Ground state configurations found in reference tables. Cannot be predicted. Bohr Configuration

Bohr Configuration of Na = 2-8-1 2 electrons in energy level 1 8 electrons in energy level 2 1 electron in energy level 3 Bohr Configuration of Na = 2-8-1

+11 Bohr Diagram of Na

Electron(s) in outermost orbit or shell Valence Electron(s)

Nucleus + all innershell electrons: Everything except the valence electrons Kernel

Electrons 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. Bohr Model

Maximum Capacity of Bohr Levels Shell # Max # of electrons 1 2 3 4 n 2 8 18 32 2n2

Bohr model Every electron is in the lowest available orbit. Ground State

Ground state configuration of Cl 2-8-7

Ground state configuration of O 2-6

Ground state configuration of Kr? 2-8-18-8 Ground state configuration of Kr?

Principle Energy Level? Shell # Principle Energy Level?

Excited State Bohr model An 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. Excited State

An excited state of O 2-5-1

An excited state of Li 2-0-1

Spectrum produced by holding a prism in sunlight Spectrum produced by holding a prism in sunlight. Contains light at every wavelength. Rainbow Continuous Spectrum

Visible 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. Bright Line Spectrum Source: http://www.dlt.ncssm.edu/TIGER/chem1.htm#atomic

Excited state E3 E2 Ground state h E1 Absorbtion of Energy

Excited state h E3 E2 Ground state E1 Emission of Energy

Orbital Modern Model Region of space that holds 2 electrons. Has a specific energy. Shapes vary. Orbital

Represents an electron dropping to a lower energy level, releasing energy in the process.