ATOMS
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What is an atom and its three subatomic
parts?
What are the charges of the three
subatomic parts?
How do you find atomic mass and the
atomic number?
Compound vs. element?
What is an isotope?
Objectives
How small is an atom?
The basic unit of matter. the smallest unit.
 ‘unable to be cut’
 Can it be seen?
 Is it living?
 100 million atoms
side by side is about
the width of your
pinkie!
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What is an atom made of?
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3 subatomic particles
◦ Proton
◦ Neutron
◦ Electron
Proton
POSITIVE PROTON (+)
 Located inside the nucleus
 Has a positive charge and contributes to
the mass
 Mass - 1.00727638 AMU
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Neutrons
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NEUTRAL NEUTRON
◦ Located inside the nucleus
◦ Has no charge but contributes to the mass
◦ Mass- 1.0086649156 AMU
Electrons
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Negative Charge
◦ Orbits around the nucleus and is in constant
motion.
◦ They are attracted to the positive charged nucleus.
◦ There are the same amount of protons as electrons.
◦ Mass is too small to be included.
◦ Mass- 0.0005446623 AMU
◦ (1/1836th the mass of a proton)
Element- pure substance containing only
one type of atom. We distinguish the
elements based on protons, neutrons, and
electrons.
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Periodic Table
Compound
A substance formed by the chemical
combination of 2 or more elements.
 The physical and chemical properties of a
compound and usually very different from
the elements in which they are formed.
 Sodium is a soft metal + poisonous
chlorine = sodium chloride
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=
+
compounds
2 or more elements
 Water =
 salt (sodium chloride) =
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Atom = smallest unit of an element
 Molecule = smallest unit of compound
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Atomic mass
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Atomic number= # of protons = # of electrons
Atomic Mass= # of protons + number of
neutrons
What does it mean?
Isotopes
Isotopes are atoms of the same element
with the same number of protons but
different number of neutrons.
 Some isotopes can give off radiation
 Isotopes are identified by their atomic
mass.
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Helium-5
Atomic Mass =
Atomic number (protons) =
Number of neutrons =
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Helium-6
Atomic Mass =
Atomic number (protons) =
Number of neutrons =
Helium-7
Atomic Mass =
Atomic number (protons) =
Number of neutrons =
Helium-8
Atomic Mass =
Atomic number (protons) =
Number of neutrons =
Isotopes
Bonds
What is the difference between a covalent
bond and an ionic bond?
 What is an ion?
 What are valence electrons?
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Chemical bonds
Ionic – electrons are transferred from one
atom to the next.
 Covalent- electrons are shared between
atoms
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Formed when one or more electrons are
transferred and ions (charged atoms)are
paired.
 What is the charge of an electron?
 When sodium looses an electron it has a
positive charge.
 Opposite ions attract!
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Ionic bonds
Valence electrons
The electrons in one atom that are able to form
bonds with another atom.
 The closer the atom is to having 8 valence
electrons , the more stable it is.
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Where are
the valence
electrons?
Ionic Bonds
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Bonds between a metal and nonmetal.
Covalent Bond
Electrons are shared between atoms.
 1 bond is when atoms share 2 electrons
 Nonmetal with nonmetal
 Neither atom is strong enough to pull an
electron away from the other so they
share.
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http://www.youtube.com/watch?v=xyY4c
WKPrSc
Can an atom be broken?
Water
- 3,000,000,000,000,000,000,000 water
molecules in a single drop of water!
Properties of water
1.
2.
3.
4.
Polarity
Hydrogen bonds
Cohesion
Adhesion
http://www.youtube.com/watch?v=ivu4nlv
D_90
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The weak interaction between the slightly
positive hydrogen and a negative atom
(oxygen, fluorine, nitrogen)
Hydrogen bonds
Cohesion
Surface Tension
Adhesion