Biology 1 Ch 2

Created by baileyrussell5 

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summer school

atom

smallest unit of matter that is unique to a particular element

proton

part of the atomic nucleus
positive charge
quantity is called the atomic number

neutron

part of the atomic nucleus
neutral charge

electron

negative charge
quantity is equal to the protons
move around the nucleus

charge

an electrical property that attracts or repels other subatomic particles

atomic number and mass number

_______ and ________ give us an idea of whether and how substances react

atomic number

number of protons in an atom and identifies that atom

mass number

total number of protons and neutrons in an atom

isotopes

atoms with the same number of protons but a different number of neutrons

12,13,14

most common isotope numbers

element

pure substances made of all the same kind of atom

periodic table

arrangement of elements based on their chemical properties

radio isotopes

unstable isotopes and tend to decay into more stable atoms
can be used in pet scans

subatomic particles

emitted when their nuclei break down

radioactive decay

process by which atoms of a radioisotope spontaneously emit energy and subatomic particles when their nucleus disintegrates

tracers

molecule with a detectable label attached

protons

electrons are attached to ______ but are repelled by other electrons

orbitals

like volumes of space around the atomic nucleus in which electrons are likely to be at any instant
contains one of 2 electrons

1,2

the shell closest to the nucleus has ___ orbital(s) holding a maximum of __ electrons

4,8

the second shell can have __ orbitals with 2 electrons each for a total of ___ electrons

unfield

atoms with _____ orbitals in their outermost shell tend to be reactive with other atoms

chemical bond

a union between the electron structures of atoms

molecule

bonded unit of 2 or more (same or different) atoms

compound

substance in which the relative percentages of 2 or more elements never vary

mixture

in a ______, 2 or more elements simply intermingle in proportions that can vary

ion

when an atom loses or gains one of more electrons, it becomes a positively or negatively charged ______

ionic bond

positive and negative charged ions are linked by mutual attraction of opposite charges

covalent bond

holds together two atoms that share one or more pairs of electrons

single bond

2 atoms sharing one pair of electrons

double bond

2 atoms sharing two pairs of electrons

triple bond

2 atoms sharing 3 pairs of electrons

nonpolar covalent bond

atoms share electrons equally

polar covalent bond

slight difference in charge between the 2 poles of the bond
ex: water

hydrogen bond

atom of a molecule interacts weakly with a hydrogen atom already taking part in a polar covalent bond

polar

water is a _____ molecule because of a slightly negative charge at the oxygen end and a slightly positive charge at the hydrogen end

hydrogen bonds

water molecules can form ______ with each other

solvent properties

the _______ of water are greatest with respect to polar molecules, with which they interact

solvent

usually liquids and can dissolve other substances

solutes

substances that are dissolved

hydrophilic

polar substance that is water loving

hydrophobic

nonpolar substance that is water dreading

cohesion

capacity to resist rupturing
especially important in pulling water through plants

surface tension

hydrogen bonding of water molecules provides cohesion which imparts ______

pH

measure of the # of hydrogen ions in a solution

acidic

0 to 7 on pH scale

base

7 to 14 on pH scale

acid

substance that releases hydrogen ions in a solution

bases

substances that releases ions that can combine with hydrogen ions

salt

ionic compound formed when an acid reacts with a base

bicarbonate

one of the body's major buffers

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