From Fish and Amphibians to

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CHEMISTRY
Chapter 2
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Essential Question
What is chemistry? How are chemicals helpful to
us?
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A. Chemistry study of the composition,
structure, properties, and reactions of a
substance.

• Life depends on chemistry . . . Because chemical
  compounds are the building blocks of life.

Discovery Streaming Clip Matter Building
blocks of the Universe
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B. MATTER
Anything that takes up space and has mass

• NOTE MASS

The quantity of matter an object has.
MASS AND WEIGHT ARE NOT THE SAME!
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C. ATOMS
1. Definition basic unit of matter
2. Atoms are composed protons(), neutrons(0),
and electrons(-)
3. Protons and neutrons are located in a central
area called the nucleus.
4. Electrons move about the nucleus. The of
electrons is equal to the of protons.
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D. ELEMENTS
1. Definition a pure substance that contains
only one type of atom
2. About 96 of the mass of all kinds of living
things is composed of a combination of just 4
elements
CARBON-C
HYDROGEN-H
OXYGEN-O
NITROGEN-N
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Image from http//www.sciencelearn.org.nz/Context
s/Just-Elemental/Sci-Media/Images/Elements-in-the-
human-body
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PERIODIC TABLE AT STATIONS... How is it
arranged? Any patterns? Columns, rows, noble
gases? Hydrogen only pink block?
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3. Periodic Tabledeveloped as a way to organize
elements

• Trends in periodic table
• Elements are found in order of atomic number (
  of protons)
• Atomic weight ( of protons of neutrons) get
  bigger as you go across and down
• Periods of elements rows
• ---As you go across a row, elements get smaller
  in size BUT greater in mass
• ---Example The go from a beach ball to a
  bowling ball
• Groups of elements columns
• Elements in the same group have similar
  properties and will bond in similar ways

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PERIODIC TABLE
GROUPS/FAMILIES
PERIOD
Atomic size decreases and atomic mass increases
As you go L to R across a period
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Information gathered from the PERIODIC TABLE
Atomic Number Chemical Symbol Element Name Atomic
Mass
Element Song
Harry Potter Elements Song
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E. Isotopes
1. definition atoms of the same element that
have different number of neutrons
2. Remember mass number number of protons plus
neutrons in nucleus of atom Example carbon-12,
carbon-13, carbon-14
Carbon 12 Carbon 13 Carbon 14
protons
neutrons
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Go to element exploration . . .
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MOST elements do not exist by themselves. . . . .
F. COMPOUNDS
1. Definition a substance formed by the bonding
of two or more elements in definite proportions
2. Chemical formula shows the composition of
the compound

• Examples H2O, NaCl, CO2

3. physical and chemical properties of compound
are DIFFERENT from each element alone
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G. Bohr Models of Atoms
1st electron shell can hold2 electrons 2nd
electron shell can hold8 electrons 3rd electron
shell can hold8 electrons

• Examples Hydrogen (1) Carbon (6)
  Oxygen (8) Chlorine (17)

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H. Chemical Bonds
1. Definition the forces that hold together the
atoms that make up compounds
2. Two main types of STRONG chemical bonds 1
ionic bonds 2 covalent bonds
. . . Lets take a look at each type more closely
. . . .
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1. Ionic bonds
---a TRANSFER of electrons takes place resulting
in ions ---ion a positively or negatively
charged atom ---ions of opposite charge attract
strongly, thus forming an ionic bond
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Example NaCl
Remember Rule 2-8-8!
The number of electrons in outer energy shell
determines the chemical properties of an
atom. Atoms want their outermost shell to be
full
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When sodium chloride (NaCl) is formed, one
electron from sodium is transferred to chlorine.
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Ionic Demo
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2. Covalent bonds
---involves SHARING of electrons ---single
covalent bond share one electron ---double
covalent bond share two electrons . .
.etc. --result of covalent bond a molecule . .
. which is the smallest unit of a
compound --Example Methane (CH4)
Covalent Demo click through tutorial reading
1-14, 22-24, and 30
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In a double bond, 2 atoms share 2 pairs of
electrons (4 electrons)
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In a triple bond, 2 atoms share 3 pairs of
electrons (6 electrons)
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Structure of the 4 elements that make up most of
the mass of living things
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