Download NOTES: 2.1 - Intro to Chemistry

NOTES: 2.1
The Nature of Matter
(Chemistry Review)
Molecular Level (DNA)
Atomic Level (Phosphorus)
VOCABULARY
● Atom
● Isotope
● Compound
● Covalent Bond
● Ionic Bond
● Molecule
● Mixture
● Solution
● Acid
● Base
Life is made up of MATTER!
● MATTER can be defined as anything
that has mass and takes up
space…this includes individual atoms!!
● just as buildings are made from bricks,
steel, glass, and wood, LIVING
THINGS are made from CHEMICAL
COMPOUNDS.
The Chemistry of Life…
● when you breathe, eat, or drink, your
body uses the substances in air, food,
and water to carry out chemical reactions
that keep you alive…
● just as an architect first must understand
the building materials, a BIOLOGIST
must first understand the compounds
that make up living things!
ATOM: smallest unit of matter that
retains the physical and chemical
properties of its element
● three subatomic particles:
Particle
Charge
Location
Mass
PROTON
+
nucleus
1.009 amu
NEUTRON
0
nucleus
-
electron
cloud
ELECTRON
1.007 amu
0.0005
amu
ATOMIC NUMBER: # of protons in an atom of an
element
● all atoms of an element have the same atomic #
● written as a subscript next to the element’s symbol
● in a neutral atom, # protons = # electrons
MASS NUMBER:
# of protons + # of neutrons
● written as a superscript next to element’s
symbol
● # of neutrons can vary in an element,
but proton # is constant
Isotopes: atoms of an element that have
different # of neutrons
● in nature, elements occur as mixtures of
isotopes
● some are radioactive: unstable isotope
where nucleus decays emitting subatomic particles and/or energy as
radioactivity causing one element to
transform into another element
Half-life: the time it takes for 50% of
radioactive atoms in a sample to decay
● Some ways radioactive isotopes are useful to
scientists:
• Ages rocks or fossils
• Treats cancer
• Kills bacteria in food
• Used as a “tracer” in human body or as a way to
label something in the body
Nitrogen vs. No Nitrogen
ELEMENT: a pure substance that
consists entirely of one type of
atom; a substance that cannot
be broken down into other
substances by chemical
reactions
Enlarged thyroid gland
caused by iodine deficiency.
COMPOUND: pure
substance composed of 2 or
more elements combined in
a fixed ratio
• examples: NaCl, H2O,
CO2, C6H12O6
• cmpds. have unique
properties beyond those of
the combined elements
Chemical Compounds
● a MOLECULE is the smallest unit of
most compounds!
● EXAMPLE: 1 molecule of water, H2O, is
the smallest unit of water possible; it
consists of 2 hydrogen atoms & 1
oxygen atom bonded together.
Energy Levels of Electrons
● Electrons are the only
subatomic particle
involved in chemical
reactions because
they occupy energy
levels surrounding the
nucleus
*IONIC BOND: bond formed by the
attraction of a positive ion to a negative
ion
-anion: negatively
charged ion; has
gained 1 or more
electrons
-cation: positively
charged ion; has
lost 1 or more
electrons
*COVALENT BOND: strong chemical
bond between atoms formed by sharing
a pair of valence electrons
Chemical Reactions
• In a chemical reaction, bonds between
atoms are formed or broken, causing
substances to combine and recombine
as different molecules;
• All of the chemical reactions that occur
within an organism are referred to as
that organism’s METABOLISM.
Chemical Equations:
• REACTANTS: the substance(s) at the
beginning of a reaction; shown on the left
side of the equation;
• PRODUCTS: the substance(s) at the end of
a reaction; shown on the right side of the
equation.
• Example:
2H2
+
O2  2H2O