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30 Cards in this Set
- Front
- Back
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ESSENTIAL ELEMENTS |
●organism needs to live & reproduce |
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What 4 elements make up 96% of living matter? |
Carbon,Hydrogen,Oxygen,Nitrogen |
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Trace elements |
●elements needed by organisms in tiny amounts |
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Subatomic particles |
●atoms are composed of these ●NEUTRONS, PROTONS, & ELECTRONS |
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Atomic nucleus |
●protons + neutrons packed together in this dense core |
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What do electrons form around an atomic nucleus? |
A cloud of negative charge |
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Dalton |
Unit of measurement ●same as AMU (Atomic Mass Unit) ●NEUTRONS & PROTONS AROUND 1 DALTON. |
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Atomic number |
●# of protons in nucleus ●written as a subscript to the left of tglhe element symbol |
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Mass number |
●sum of protons & neutrons ●written as a subscript in the upper left of the element symbol |
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Atomic mass |
●total mass of an atom |
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WHEN AN ATOM HAS MORE NEUTRONS THAN OTHER FORMS OF THAT ELEMENT, IT IS CALLED... |
AN ISOTOPE |
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If an atom of helium were the size of a football stadium, the NUCLEUS would be the size of... |
A pencil eraser |
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Where are the 3 electron shells located in relation to the nucleus? |
1st- closest to nucleus 2nd- middle to nucleus 3rd- farthest from nucleus |
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How many electrons can the 1st shell of an atom hold? |
ONLY 2 |
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HOW MANY ELECTRONS CAN EACH SHELL >1 HOLD? |
8 |
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Covalent bond |
●sharing of a pair of electrons of valence electrons by 2 atoms |
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What is an atom's valence? |
● # of covalent bonds an atom can form ● usually = # of unpaired electrons in its valence shell |
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Electronegativity |
●attraction of an atom for the electrons of a covalent bond |
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THE MORE ELECTRONEGATIVE AN ATOM IS, THE MORE STRONGLY IT PULLS SHARED ELECTRONS TOWARDS _________. |
Itself |
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NONPOLAR COVALENT BOND |
Electrons are shared EQUALLY between 2 atoms of similar electronegativity ●ex: H2, O2 |
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POLAR COVALENT BOND |
When an atom is bonded to a more electronegative atom ELECTRONS NOT SHARED EQUALLY ex: H2O. Oxygen = super electronegative... electrons spend more time near the oxygen |
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IONIC BOND |
Chemical bond resulting from the attraction between oppositely charged ions |
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Hydrogen bond |
●weak chemical bond ●slightly pos H atom in a molecule is attracted to slightly neg atom in another molecule or in another region of the same molecule |
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COHESION |
Linking together of like molecules Usually by hydrogen bonds |
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Adhesion |
Clinging of one substance to another Ex:water to plant cell walls |
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Specific heat |
Amount of heat that needs to be absorbed/lost to change 1g of a substance 1°C |
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HYDRATION SHELL |
Sphere of water molecules around each dissolved ion |
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BUFFER |
Substance that minimalizes changes in the concentrations of h+ and oh- in a solution |
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An atom's valence |
# of covalent bonds it can form |
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Enzymes |
Specialized macromolecules (usually proteins) Speed up chemical reactions |
