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Chemistry
• Atomic structure
• ATOMS, ATOMS, ATOMS!!!!!!!!
Atoms
• Atoms—tiniest part of an element that still
has the element’s properties
• They are too small to see with the naked
eye.
• The term atom is Greek and means “too
small to be divided”
Atoms2
• Atoms are made up of three subatomic
particles:
– Neutrons
– Protons
– Electrons
Subatomic particles
• The nucleus:
– The nucleus is the center of the atom, contains
the protons and neutrons, and makes up the
mass of the atom.
– The protons and neutrons make up all of the
mass of an atom
– The neutron has no charge to it
– The proton has a positive charge (p for positive)
Subatomic particles2
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Orbiting around the nucleus are the electrons.
They have a negative charge.
They are extremely small.
They are so small that their mass is not
included in the element’s atomic mass.
• Electrons are located in energy levels outside
of the nucleus.
• The electrons in the highest energy level are
called valence electrons.
Atom Joke
A proton, neutron, and electron went out to dinner
one night. After a luxurious meal, the waiter
brought the check to the proton and the
electron. The neutron was perplexed as to why the
waiter didn't bring him his check. So, he
summoned the waiter to the table and asked him
about it.
The waiter explained to the neutron, "For you,
there's no charge!“
Haaaaaaaaaa! Haaaaaa! Haaaaaaaaaaaa!
Model of an atom
Atoms and the Periodic Table
• All of the world’s known elements are on the
periodic table.
• The elements atomic number tells the
element’s number of protons and electrons.
• The element's atomic mass tells the
element’s number of protons and neutrons
added together.
Elements on the Periodic
Table
How many neutrons?
• An atom’s mass is made out of neutrons and
protons.
• If copper has an atomic mass of 64 grams
and has an atomic number of 29 how many
neutrons does it have?
• Mass=neutrons + protons
• 64= neutrons + 29 (the atomic number is the
number of protons)
• 64- 29=35 neutrons!!!
Atoms and charges
• What happens when an atom gains or looses
an electron?
• The atom becomes charged!
– Example: Copper has an atomic number of 29.
This means copper has 29 electrons(-) and 29
protons(+). If copper were to loose two
electrons, what would copper’s charge be?
29 Protons (+)
+ 27 Electrons (-)
2 Protons left over, each proton has a positive
charge so the charge of copper would be +2!
Practice Problem
• Oxygen has an atomic number of 8 and an
atomic mass of 16. How many neutrons
does oxygen have?
• Answer: 16= N+8, N=8
• What would Oxygen’s charge be if it gained
two electrons?
• Answer: 8(+ protons) + 10 (- electrons)=-2
Atom Joke
Two atoms are walking down the street and
ones says to the other, “Hey hold up. I
think I lost an electron.” The second atom
replies, “Are you sure?” The first atom
exclaimed, “I’m positive!!!”
HA! HA! HA! HA!