Biology

is a substance that cannot be broken down to other substances by ordinary chemical means.

there are 92 natural elements on earth

25 of the 92 natural elements are essential to life

Carbon (C)

Oxygen (O)

Nitrogen (N)

Hydrogen (H)

an element that is essential for life but required in extremely minute amounts

is a substance consisting of two or more different elements combined in a fixed ratio.

element to compound

-ex: NaCl (sodium choloride)=table salt

smallest unit of matter that retains properties of an element

have the same number of protons and electons but different number of neutrons

-pg. 20, table 2.3

an energy level representing the distance of an elctron from the nucleus of an atom.

an atom may have 1, 2, or 3 electron shells

the 1st electron shell has only one orbital and can hold only 2 electrons.

the second and third rows, the outer shell has four orbitals and can hold up to 8 electrons (4 pairs)

ion: is an atom or molecule with an electrical charge resulting from a gain or loss of one or more electrons

molecule: two or more atoms held together by covalent bonds

reactant: conversion of the starting materials

product: the material resulting from the chemical reaction

ionic bond: 2 ions with opposite charges that attract eachother and the ions are held togeher (opposites attract)

covalent bond: the strongest kind of chemical bond in which two atoms share one or more paris of outer-shell electrons.

hydrogen bond: a type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule

nopolar covalen bond: equal pull between atoms

polar covalent bond: unequal pull between atoms of different elements/electonegativities-polar molecules

1: cohesion, adhesion, surface tension

2: resists temperature change

3: water can exist as a gas, liquid, and solid. it is less dense as a solid due to hydrogen bonding

4: solvent of life: solvent (the dissolving agent) and solute (the substance dissolved)

the sticking together of molecules of the same kind, often by hydrogen bonds.

attraction between different kinds of molecules

a measure of how difficult it is to break the surface of a liquid-hydrogen bonds are responsible for surface tension (ex: bg able to float in water)

energy associated with movement of atoms and molecules in matter

measures the intensity of heat

liquid consisting of a uniform mixture of two or more substances

the dissolving agent of a solution

a substanc that is dissolved in a solution

acid: substance that increases the hydrogen ion concentration in a solution (H+) hydrogen ions

Base: substance that increase the hydrogen ion concentration in a solution (OH-) hydroxide ions

buffer: a chemical substanc that resists changes in pH by accepting hydrogen ions from or donating hydrogen ions to solutions.

hydrogen ions are acids

hydroxide ions are base

acids from 0 to 6

7 is neutral

base from 8 to 14

*concentration is 10x greater each step

they are between 7 to 7.8