CHEMISTRY AND LIVING THINGS Why is chemistry important in biology? • Organisms are made of macro-________. • Macromolecules are made of smaller _______, made of atoms.
CHEMISTRY AND LIVING THINGS Why is chemistry important in
biology?• Organisms are made of macro-
________.• Macromolecules are made of
smaller _______, made of atoms.
Atoms
The Smallest piece of an ________. ________ is made up of atoms
Subatomic Particle
Charge Location
Proton (+) Nucleus
Neutron No charge Nucleus
Electron (-) Outside Nucleus
Bohr Model: What makes a nickel different from a piece of gold?
VALENCE ELECTRONS:THE OUTER SHELL OF ELECTRONS DETERMINES AN ATOM’S PROPERTIES.
Elements & Periodic Table
Element= A substance made up of __ type of atom 92 natural elements more than 113 total Arranged in the Periodic Table based on atomic number
and common properties
ISOTOPES Isotopes= Atoms of the same element
that differ in the number of neutrons they contain are known as isotopes
The sum of the protons and neutrons in the nucleus of an atom is called its mass number.
Atomic Number
Atomic Mass
C6
12.01
# of Protons
P + N
* The number of protons equals the number of electrons!
P+
6
N 6
E- 6
ISOTOPES
Isotopes are identified by their mass numbers.
For example, carbon has three isotopes—carbon-12, carbon-13, and carbon-14. Each isotope has a different number of neutrons.
ISOTOPES Because they have
the same number of electrons, all isotopes of an element have the same chemical properties.
RADIOACTIVITY Radioactive Isotopes
Some isotopes are radioactive, meaning that their nuclei are unstable and break down at a constant rate over time.
Although the radiation these isotopes give off can be dangerous, they have important scientific and practical uses.
RADIOACTIVITY
• Radioactive isotopes can be used: to determine the ages of rocks and fossils. to treat cancer. to kill bacteria that cause food to spoil. as labels or “tracers” to follow the
movement of substances within an organism.
Chemical Compounds
The same way atoms combine to form elements, elements combine to form compounds.
Compounds have different properties than the elements that make them up.
Water (H20)
Ahh… Nirvana
All atoms want to have a full outer shell 1st level = 2 electrons All other shells = 8 electrons As you move to the right of the periodic table,
the elements are getting closer to a full outer shell.
How do atoms combine?
Covalent Bonds• Sharing of electrons
• Ionic Bonds•Giving/Taking of electrons• Ions – charged atoms
IONIC BONDS An atom that loses electrons has a positive
charge. An atom that gains electrons has a negative
charge. These positively and negatively charged
atoms are known as ions.
COVALENT BONDS= SHARING
Terms to know
Atom Proton, Neutron, Electron
Element Atomic Mass Atomic Number Compound Covalent Bond Ionic Bond