Chemistry Review
Atoms, elements & Isotopes
How Big is an Atom?
How Many Cuts?Cut 1 14.0 cm 5.5" Child's hand, pocketsCut 2 7.0 cm 2.75" Fingers, ears, toesCut 3 3.5 cm 1.38" Watch, mushroom, eyeCut 4 1.75 cm .69" Keyboard keys, rings, insectsCut 6 .44 cm .17" Poppy seedsCut 8 1 mm .04" Thread. Congratulations if your still in!Cut 10 .25 mm .01" Still cutting? Most have quit by nowCut 12 .06 mm .002" Microscopic range, human hairCut 14 .015 mm.006" Width of paper, microchip componentsCut 18 1 micron .0004" Water purification openings, bacteriaCut 19 .5 micron .000018" Visible light wavesCut 24 .015 micron .0000006" Electron microscope range, membranesCut 31 .0001 micron .0000000045" The size of an Atom!
I. Atoms
A. the basic unit of matter B. matter is anything that takes up space and
has massC. all things are made of atomsD. microscopic … need special microscope to
view1. 100 million atoms lined up in a row
would only measure 1 cm long
E. Atomic Structure/components1. Subatomic particles:
a. protons 1- positive charge
2- mass weight 1.0073 b. neutrons 1- no charge 2- mass weight 1.0087 c. electrons 1- negative charge 2- mass weight 0.000549
All atoms have the same amt of protons and electrons
Atomic number - # of protons Atomic Mass - #p + #n
You can see an atom with your eyes?
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1. True2. False
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An atom has weight
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1. True 2. False
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Which subatomic particle is located outside the nucleus of an atom?
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1. Electron2. Neutron3. Proton
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The positively charged particle in an atom the
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1. Electron2. Neutron 3. Proton
Protons and ______ are found inside the nucleus.
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1. Electrons2. Neutrons 3. Protons
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The negatively charged particle in the atom is the
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1. Electron2. Proton3. Neutron
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Which combination of particle and charge is correct?
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1. Proton: negative charge2. Electron: positive charge3. Neutron: negative charge4. Neutron: no charge
II. Elements & Isotopes A. Element is a substance that cannot be broken down B. Elements are made up of lots and lots of the same kind of atom C. more than 100 elements known 1. represents with a single or 2 letters D. only about 2 dozen in living organisms 1. examples – Ca, O, H, C, N, P, K, S, Na, Li, Zn, Mg, Cu, Fe, Se, I, F Co, Al, Si, Br, Ar, Mn, Sr, Pb, V E. Essential Elements of Life: C H N O P S Ca K
F. Isotopes 1. atoms of the same element that have differ masses due to the differ number of neutrons on the nucleus a. example: Carbon -12 ; Carbon -13; Carbon – 14 b. all isotopes have the same chemical properties
G. Radioactive Isotopes 1. isotopes that give off radioactivity and have unstable nuclei 2. these isotopes break down at a consist rate after a period of time 3. although very dangerous, can be helpful
a. Aging Fossils/Rocks b. Treat cancer c. Radioactive “tags” – trace substances d. PET scan (CT scan)
III. Compounds
A. a substance made of 2 or more elements 1. example – H2O
B. held together by chemical bonds
C. main types: - ionic- covalent bond- hydrogen - van der waals
Isotopes weight the same.
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1. True 2. False
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Radioactive isotopes are good
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1. True 2. False
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Two or more different atoms are combined to form a
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1. Symbol2. Element3. Isotope4. Compound
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In which if the following way do isotopes of the same element differ?
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1. In number of neutrons only
2. In number of protons only
3. In number of protons & mass
4. In number of neutrons & mass
D. Ionic bonds 1. formed when 1 or more electrons are transferred from 1 atom to another a. opposite charges attract to form an ionic bond (Na(+)) (Cl(-)) b. when atoms lose electrons, the atoms becomes positive c. when atoms gain electrons, they become negative 2. when an atom becomes positively or negatively charged, they become known as ions a. if positively charged known as cation b. if negatively charged known as anion
E. Covalent bonds
1. forms when electrons are shared between atoms 2. Two types a. polar covalent
1- unequal sharing due to size differences 2- example: H2O
b. nonpolar covalent 1- equal sharing of electrons
F. Hydrogen Bonds
Hydrogen bond is the weak attraction between δ+ of H and δ- of O or N of a different molecule
G. Van der Waals Interactions 1. Electrons move creating weak positive and negatively charged regions (even if non- polar) 2. named after the scientist 3. can hold even large molecules together 4. geckos show this force
a. climbing up the smoothest surface, geckos can hold on even with 1 toe b. a gecko foot is covered w/ half million projections
c. the projections are dived into 100s of tiny flat fibers designed to come onto contact with a surface at the molecular level
d. van der waals forces form btwn the surface molecules and the gecko foot
e. when a gecko wants to move it peels its foot off at angle then reapplies it elsewhere on the surface
A covalent bond is formed by
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1. Transferring of electrons
2. Sharing electrons3. Losing electrons4. Gaining electrons
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Ionic bonds are formed when
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1. Transferring of electrons
2. Sharing electrons3. Losing electrons4. Gaining electrons
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The gecko is an example of
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1. Covalent bonds2. Ionic bonds3. Hydrogen bonds4. Van der Waals
forces
When an atom loses electrons it becomes a ______ ion
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1. Positively charge
2. Negatively charged
3. Neutral
There are three types of covalent bonds
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1. True 2. False
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Polar covalent is the unequal sharing of electrons
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1. True 2. False
IV. Representing AtomsA. Bohr Model (e cloud)
1. Use element or # protons/neutrons in nucleus
2. Surrounding by energy shells w/e a. 2 electrons in first shell
b. 8 electrons in 2nd c. 18 electrons in 3rd shells
B. Lewis Dot Structures 1. Use element symbol 2. Use dots to represent 3. valence electrons only
The Bohr Model shows how many electrons the element has
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1. True2. False
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The Lewis dot model shows all electrons an element has
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1. True2. False
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Questions
ASSIGNMENT:
Review questions
