Ch #2 - Basic Chemistry

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BIO-LECTURE-1141
 
Term  
Definition

Elements

Substances that cannot be broken down into simpler substances by chemical means *112 (116) known elements (92 natural)

Major Elements of the body

oxygen, carbon, hydrogen, and nitrogen

Atoms

-Individual particle of an element

-Demonstrate the properties of an element

-Atomic symbols: O, C, H, N

Parts of an Atom

(Atoms are neutral)

NUCLEUS

-Protons: positively charged particles (p+)

-Neutrons: neutral particles (n0) -99% of the mass of the atom -each proton and neutron is ~1 amu

ELECTRON CLOUD

-Electrons - negatively charged particles (e-)

Identifying Elements

*Atomic number (# of protons) -Unique for each element -Indicates number of electrons

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Isotopes

=When an elements has 2 different numbers of neutrons in its atoms

*Atomic weight = average of isotopes

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Matter

*Molecule - combination of 2 or more atoms

*Mixtures:

-Solutions= homogeneous mixtures (sea water)

-Colloids= heterogeneous mixtures that do not settle (Jell-O)

-Suspensions = heterogeneous mixtures that settle over time (sand/water or blood)

Chemical Bonds

*Ionic

*Covalent -Polar -Non polar

*Hydrogen

BONDS- all about electrons

*It matters whats in the electron shell (2, 10, 18)

*Atoms like stability (valence shell and octet rule)

*Atoms can give up or take electrons (ions)

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Ions

*Ions= Particles with charge (fewer or more electrons than protons)

*Sodium (Na) - 11e- and 11p+ (2+8=10) - cation

*Fluorine (F) - 9e- and 9p+

*F- - 10e- and 9p+ - anion

*Neon (Ne) is a Noble Gas and is inert - 10e- and 10p+

Ionic Bonding

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Ionic Bonds

*Between anions and cations

*Cation (+) donates electron to anion (-) creating permanent charges (electron transfer)

*Form crystals of alternating + and -

*Polyatomic ions in biology

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Covalent Bonds

*ELECTRON SHARING to stabilize valence shell

*Atoms can share with more than one atom

*Atoms share with the same atom 2 or 3 times -Double & triple bonds

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Polar vs. Nonpolar

*NONPOLAR- electronically balanced/equal sharing

*POLAR- electronically unbalanced/unequal sharing

-Most common atoms = (O and N) -Dipole

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Summary Chemical Bonds

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Hydrogen Bonds

-Forms in polar molecules

-Intermolecular = forms between hydrogen and electronegative atom on other molecule

  • Weak bond that stablizes

-H2O, DNA (base pairs), proteins (folding)

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Chemical Reactions

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Dehydration Synthesis and Hydrolysis

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Energy & Reversibility

*Exergonic reactions release energy -Energy can be harnessed by body

*Endergonic reactions require energy -Energy must be expended by the body

*All reactions are reversible - A + B ----> AB

WATER, the solvent of life

SLIDE 22*