Atomic Structure

Basic Parts of the atom- Subatomic Particles Proton Positive charge Found in the nucleus Dictate the identity of the atom Neutron No charge Found in the nucleus Electron Orbits the nucleus Tiny compared to proton and neutron # equal to # of protons in neutral atom

Parts of the atom Nucleus Consists of protons and neutrons Extremely dense If the nucleus of an atom was the size of a 1cm ball, it would weight 133,000,000 tons! Electron cloud Area outside the nucleus where the electrons orbit the nucleus Empty space If the nucleus was the size of golf ball, the electron cloud would be half a mile in diameter

Electron Clouds Only a certain # of electron can occupy a particular area at once Known as energy levels Level 1- 2 electrons Level 2- 8 electrons Level electrons Level electrons

Identifying Atoms Atomic Number Determined by the number of protons All atoms of a particular element will have the same atomic number Different elements have different atomic numbers

LecturePLUS Timberlake 6 Atomic Number on the Periodic Table 11 Na Atomic Number Symbol

LecturePLUS Timberlake 7 All atoms of an element have the same number of protons 11 Na 11 protons Sodium

Checkpoint! Oxygen Neon Iron Lithium Phosphorous Mercury What is the atomic number for the following elements?

LecturePLUS Timberlake 9 Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons

Atomic Mass The mass of the nucleus of an atom Protons + neutrons If we know atomic mass and atomic number, we can determine the number of neutrons

Checkpoint! Oxygen Neon Iron Lithium Phosphorous Mercury What is the atomic mass for the following elements? How many neutrons would each element have?

Using Bohr Model to show atomic structure

Isotopes Atoms of the same element whose atomic masses are different Two ways of identifying Hyphen notation element name-atomic mass Ex- Carbon-12 Chemical notation (nuclear symbol) atomic mass written over atomic number followed by atomic symbol Ex: C Again, we can identify # of neutrons from atomic mass and atomic number 12 6

Nitrogen atom with 7 neutrons Carbon atom with 8 neutrons Sulfur atom with 15 neutrons Lithium atom with 2 neutrons Neon atom with 12 neutrons Write the Chemical formula and hyphen notation for the following: Checkpoint!

Relative Atomic Mass atomic mass unit (amu)- one is exactly 1/12 th of the mass of a carbon-12 atom mass of proton= amu mass of neutron= amu mass of electron= amu

Weighted average of masses of all naturally occurring isotopes of an element This is the value you see on the periodic table Calculated by multiplying each isotopes mass by the decimal percentage and adding those values together. EX: Carbon-12: 98.5% Carbon-13: 1.0% Carbon-14: 0.5% Average Atomic Mass

Uranium-234: 0.005% Uranium-235: 0.720% Uranium-238: % Copper-63: 69.17% Copper-65: 30.83% Calculate the average atomic mass for the following: Checkpoint!