THE CHEMISTRY OF LIFE The Nature of Matter. What do all of These Pictures Have in Common?
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Transcript of THE CHEMISTRY OF LIFE The Nature of Matter. What do all of These Pictures Have in Common?
MATTER• All matter is made up of different
combinations of elements.
• Atom = the smallest quantity of an element that still has the characteristics of it.
• Atoms are made up of even smaller (subatomic) particles: protons, neutrons, and electrons.
THE NUCLEUS• The core of an atom.• It holds 99.9% of the
mass of the atom.• It is small compared to
the whole atom.– Most of atom is empty
space around the nucleus.
– If nucleus of one atom were 1cm wide, the size of the atom would cover 30 football fields.
• It is made up of Protons and Neutrons.
• Electrons orbit around the nucleus.
PROTONS• Have a positive (+) charge.
• Found inside the nucleus of an atom.
• Each element has a different number of protons.
• Atomic Number = the number of protons in an atom.
• Proton # never changes in an element.
NEUTRONS• Have no charge = “neutral”
• Found in the nucleus of an atom.
• Atoms of an element don’t always have the same # of neutrons.
• These atoms are called isotopes.
ELECTRONS• Have a negative (-) charge.• Orbit around the nucleus.• It is always in motion.• Travels at the speed of light.• It is 2,000 times smaller than a Proton
or a Neutron.– If the nucleus is 1cm wide, the Electrons
would be smaller than the width of a strand of hair.
THE ATOM• ProtonsHave a positive charge (+)
• NeutronsHave no charge
• ElectronsHave a negative charge (-)
• The nucleus = Protons + Neutrons.
• Surrounding the nucleus = Electrons.
ATOMIC NUMBER• The number of Protons in the nucleus of
an atom.• The number of Protons = the number of
Electrons.
ATOMIC MASS• The number of Protons + the number of
Neutrons.– Find the atomic mass of an atom that has
10 protons, 8 neutrons, and 10 electrons.– An atom has:
• Atomic Number = 8• Atomic Mass = 20
How many Protons, Neutrons and Electrons does it have?
THE ATOM• The nucleus = +
charge.• The electron cloud =
- charge.• Nucleus and
electron cloud are attracted to each other.
• “Opposites Attract”
ELECTRON ORBITS• 1st orbit = 2 e-
• 2nd orbit = 8 e-
• 3rd orbit = 8 e-
• 4th orbit = 16 e-
• The atom is always looking to fill up its outermost orbit.
ELEMENTS• Element = A pure
substance made up of only one kind of atom.
• Each element has a unique atomic number.
• Which one of these is an element?
PERIODIC TABLE OF ELEMENTS
• Elements are categorized by atomic number = number of protons.
• Who created the Periodic Table of Elements?
ISOTOPES
• IsotopesAtoms of an element that have different number of neutrons.– Ex. Carbon-12, Carbon-13, Carbon-14
• All isotopes of an element have the same chemical properties:– Same number of electrons.
STOP AND REVIEW• ATOM• ATOMIC NUCLEUS• PROTONS• NEUTRONS• ELECTRONS• ATOMIC NUMBER• ATOMIC MASS
• ATOMIC STRUCTURE
• VALENCE ELECTRONS
• ELEMENT• PERIODIC TABLE• ISOTOPES
COMPOUNDS• Compound =
Substance made up of atoms of two or more different elements.
• Compounds are joined by chemical bonds.
• They can be broken down into simpler substances.
+
Sodium Chlorine
Sodium Chloride = Table salt
CHEMICAL BONDS• Covalent Bond = Forms
when two or more atoms share electrons to form a molecule.
• If the electrons are shared equally = nonpolar bond.
• If electrons are NOT shared equally = polar bond. – Ex. H2O (hydrogen bonds)– Who does it remind you
of?
MOLECULES• Molecules = The structure that results when
two atoms are joined by covalent bonds.• Physical and chemical characteristics are
different from the elements that make it up.
CHEMICAL BONDS• Ionic Bond = One
atom pulls the shared electrons away from the other atom. (greedy)
• Ion = An atom or molecules that has gained or lost one or more electrons.
• Ex. Na+, Cl-
--Ionic bond between sodium (Na) and Chlorine (Cl) = Na+ and Cl- ions
http://www.visionlearning.com/library/module_viewer.php?c3=&mid=55&ut=&l=e
http://www.sciencejoywagon.com/chemzone/lessonch/03bonding/dogbond/default.htm
QUESTIONS
• What is the basic structure of an atom?
• Give one example of a compound?
• What is the difference between a covalent bond and an ionic bond?
• Why do all isotopes of an element have the same chemical properties?
QUESTIONS• Two or more different atoms are
combined in definite proportions in any:– A. Symbol– B. Isotope– C. Element– D. Compound