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 Cloudss•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 3- 18 electrons•Level 4- 32 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

•Checkpoint!

•Oxygen

•Neon

• Iron

• Lithium

• Phosphorous

•Mercury

• What is the atomic number for the following elements?

•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?

• 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!

• 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: 99.275%

Copper-63: 69.17%Copper-65: 30.83%

• Calculate the average atomic mass for the following:

•Checkpoint!