Chapter 2 Flashcards
matter
anything that occupies space and has mass.
mass
the amount of matter in an object
weight
the gravitational force acting on an object of a given mass.
kilogram ( kg )
the international unit for mass
gram (g)
1/1000 the mass of a kilogram
element
the simplest type of matter, having unique chemical properties.
atom
the smallest particle of an element that has the chemical characteristics of that element.
neutron
has no electrical charge
proton
has one positive charge
electron
has one negative charge
nucleus
protons and neutrons form the nucleus at the center of an atom; electrons move around the nucleus; nucleus accounts for 99.97% of an atom’s mass but only 1 ten-trillionth of its volume; most of the volume of an atom is occupied by the electrons.
electron cloud
the region where the electron is most likely to be found
atomic number
equal to the number of protons in each atom and, because the number of electrons is equal to the number of protons,
the atomic number is also the number of electrons.
mass number
the number of protons plus the number of neutrons in each atom.
Isotopes
two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons
dalton (Da)
a system of relative atomic mass scientists use to avoid working with such small numbers; unified atomic mass unit ( u ) is 1/12 the mass of 12 C, a carbon atom with 6 protons and 6 neutrons. Thus, 12 C has an atomic mass of exactly 12 Da.
atomic mass
the average mass of an element’s naturally occurring isotopes, taking into account the relative abundance of each isotope.
Avogadro’s number or 1 mole (mol)
chemist groups atoms in lots of 6.022 x 10 ^23
molar mass
The mass of 1 mole of a substance expressed in grams
chemical bonding
When the outermost electrons are transferred, or shared, between atoms; the outermost electrons of an atom determine its chemical behavior.
ion
a charged particle, formed when an atom loses or gains electrons resulting in unequal numbers of protons and electrons
cations
Positively charged ions
anions
negatively charged ions
ionic bond
a bond when a cation and anion is bonded together; cations and anions tend to remain close together because oppositely charged ions are attracted to each other
covalent bond
forms when atoms share one or more pairs of electrons; the resulting combination of atoms is called a molecule.
single covalent bond
the sharing of one pair of electrons by two atoms
double covalent bond
when two atoms share 4 electrons, 2 from each atom; Double covalent bonds are indicated by a double line between the atoms
nonpolar covalent bonds
when electrons are shared equally between atoms
polar covalent bonds
when elections are not shared equally between atoms; atoms bound to one another by a covalent bond do not
always share their electrons equally because the nucleus of one atom attracts the electrons more strongly than does the nucleus of the other atom
molecule
composed of two or more atoms chemically combined to form a structure that behaves as an independent unit.
compound
a substance resulting from the chemical combination of two or more different types of atoms.
Alpha particles
positively charged helium ions which consist of 2 protons and 2 neutrons.
Beta particles
electrons formed as neutrons change into protons. An electron is ejected from the neutron, and the proton that is produced remains in the
nucleus.
Gamma rays
a form of electromagnetic radiation (high-energy photons) released from nuclei as they lose energy.
molecular mass
can be determined by adding up the atomic masses of its atoms (or ions).
intermolecular forces
Weak electrostatic attractions that exist between the oppositely charged parts of molecules, or between ions and molecules
hydrogen bond
If the positively charged hydrogen of one molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another molecule
Solubility
the ability of one substance to dissolve in another
dissociate
separate; When ionic compounds dissolve in water, their ions dissociate from one another because the cations are attracted to the negative ends of the water molecules, and the anions are attracted to the positive ends of the water molecules.
electrolytes
Cations and anions that dissociate in water; have the capacity to conduct an electrical current
nonelectrolytes
Molecules that do not dissociate form solutions that do not conduct electricity
chemical reaction
when atoms, ions, molecules, or compounds interact either to form or to break chemical bonds.
reactants
The substances that enter into a chemical reaction
products
the substances that result from the chemical reaction
When two or more reactants chemically combine to form a new
and larger product, the process is called a synthesis reaction .
When two or more reactants chemically combine to form a new
and larger product, the process is called a synthesis reaction .
dehydration reactions
Synthesis reactions in which water is a product
anabolism
All of the synthesis reactions that occur within the body; The growth, maintenance, and repair of the body could not take place without anabolic reactions.
decomposition reaction
reverse of a synthesis reaction; a larger reactant is chemically broken down into two or more smaller products.
hydrolysis reactions
reactions that require water to be split into two parts and that each part be contributed to one of the new molecules.
catabolism
The decomposition reactions that occur in the body
metabolism
All of the anabolic and catabolic reactions in the body
reversible reaction
when the reaction can proceed from reactants to products or from products to reactants.
equilibrium
When the rate of product formation is equal to the rate of the reverse reaction
oxidation
The loss of an electron by an atom
reduction
gain of an electron
oxidation-reduction reactions
when one atom partially or completely loses an electron and another atom gains that electron