CHM 1045 - Exam 1

Terms pulled from the Atom's First textbook (vocab chapters 1-3)

accuracy

how closely a measurement aligns with a correct value

atom

smallest particle of an element that can enter into a chemical combination

Celsius (°C)

unit of temperature; water freezes at 0 °C and boils at 100 °C on this scale

chemical change

change producing a different kind of matter from the original kind of matter

chemical property

behavior that is related to the change of one kind of matter into another kind of matter

chemistry

study of the composition, properties, and interactions of matter

compound

pure substance that can be decomposed into two or more elements

cubic centimeter (cm3 or cc)

volume of a cube with an edge length of exactly 1 cm

cubic meter (m3)

SI unit of volume

density

ratio of mass to volume for a substance or object

dimensional analysis

(also, factor-label method) versatile mathematical approach that can be applied to computations ranging from simple unit conversions to more complex, multi-step calculations involving several different quantities

element

substance that is composed of a single type of atom; a substance that cannot be decomposed by a chemical change

exact number

number derived by counting or by definition

extensive property

property of a substance that depends on the amount of the substance

Fahrenheit

unit of temperature; water freezes at 32 °F and boils at 212 °F on this scale

gas

state in which matter has neither definite volume nor shape

heterogeneous mixture

combination of substances with a composition that varies from point to point

homogeneous mixture

(also, solution) combination of substances with a composition that is uniform throughout

hypothesis

tentative explanation of observations that acts as a guide for gathering and checking information

intensive property

property of a substance that is independent of the amount of the substance

kelvin (K)

SI unit of temperature; 273.15 K = 0 ºC

kilogram (kg)

standard SI unit of mass

law

statement that summarizes a vast number of experimental observations, and describes or predicts some aspect of the natural world

law of conservation of matter

when matter converts from one type to another or changes form, there is no detectable change in the total amount of matter present

length

measure of one dimension of an object

liquid

state of matter that has a definite volume but indefinite shape

liter (L)

(also, cubic decimeter) unit of volume; 1 L = 1,000 cm3

macroscopic domain

realm of everyday things that are large enough to sense directly by human sight and touch

mass

fundamental property indicating amount of matter

matter

anything that occupies space and has mass

meter (m)

standard metric and SI unit of length; 1 m = approximately 1.094 yards

microscopic domain

realm of things that are much too small to be sensed directly

milliliter (mL)

1/1,000 of a liter; equal to 1 cm3

mixture

matter that can be separated into its components by physical means

molecule

bonded collection of two or more atoms of the same or different elements

physical change

change in the state or properties of matter that does not involve a change in its chemical composition

physical property

characteristic of matter that is not associated with any change in its chemical composition

plasma

gaseous state of matter containing a large number of electrically charged atoms and/or molecules

precision

how closely a measurement matches the same measurement when repeated

pure substance

homogeneous substance that has a constant composition

rounding

procedure used to ensure that calculated results properly reflect the uncertainty in the measurements used in the calculation

scientific method

path of discovery that leads from question and observation to law or hypothesis to theory, combined with experimental verification of the hypothesis and any necessary modification of the theory

second (s)

SI unit of time

SI units (International System of Units)

standards fixed by international agreement in the International System of Units (Le Système International d’Unités)

significant figures

(also, significant digits) all of the measured digits in a determination, including the uncertain last digit

solid

state of matter that is rigid, has a definite shape, and has a fairly constant volume

symbolic domain

specialized language used to represent components of the macroscopic and microscopic domains, such as chemical symbols, chemical formulas, chemical equations, graphs, drawings, and calculations

temperature

intensive property representing the hotness or coldness of matter

theory

well-substantiated, comprehensive, testable explanation of a particular aspect of nature

uncertainty

estimate of amount by which measurement differs from true value

unit

standard of comparison for measurements

unit conversion factor

ratio of equivalent quantities expressed with different units; used to convert from one unit to a different unit

volume

amount of space occupied by an object

weight

force that gravity exerts on an object

alpha particle (α particle)

positively charged particle consisting of two protons and two neutrons

anion

negatively charged atom or molecule (contains more electrons than protons)

atomic mass

average mass of atoms of an element, expressed in amu

atomic mass unit (amu)

(also, unified atomic mass unit, u, or Dalton, Da) unit of mass equal to 1/12 of the mass of a 12C atom

atomic number (Z)

number of protons in the nucleus of an atom

cation

positively charged atom or molecule (contains fewer electrons than protons)

chemical symbol

one-, two-, or three-letter abbreviation used to represent an element or its atoms

Dalton (Da)

alternative unit equivalent to the atomic mass unit

Dalton’s atomic theory

set of postulates that established the fundamental properties of atoms

electron

negatively charged, subatomic particle of relatively low mass located outside the nucleus

empirical formula

formula showing the composition of a compound given as the simplest whole-number ratio of atoms

fundamental unit of charge

(also called the elementary charge) equals the magnitude of the charge of an electron (e) with e = 1.602 × 10−19 C

ion

electrically charged atom or molecule (contains unequal numbers of protons and electrons)

isomers

compounds with the same chemical formula but different structures

isotopes

atoms that contain the same number of protons but different numbers of neutrons

law of constant composition

(also, law of definite proportions) all samples of a pure compound contain the same elements in the same proportions by mass

law of definite proportions

(also, law of constant composition) all samples of a pure compound contain the same elements in the same proportions by mass

law of multiple proportions

when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small whole numbers

mass number (A)

sum of the numbers of neutrons and protons in the nucleus of an atom

molecular formula

formula indicating the composition of a molecule of a compound and giving the actual number of atoms of each element in a molecule of the compound.

neutron

uncharged, subatomic particle located in the nucleus

nucleus

massive, positively charged center of an atom made up of protons and neutrons

proton

positively charged, subatomic particle located in the nucleus

spatial isomers

compounds in which the relative orientations of the atoms in space differ

structural formula

shows the atoms in a molecule and how they are connected

structural isomer

one of two substances that have the same molecular formula but different physical and chemical properties because their atoms are bonded differently

unified atomic mass unit (u)

alternative unit equivalent to the atomic mass unit

actinide

inner transition metal in the bottom of the bottom two rows of the periodic table

alkali metal

element in group 1

alkaline earth metal

element in group 2

amplitude

extent of the displacement caused by a wave

atomic orbital

mathematical function that describes the behavior of an electron in an atom (also called the wavefunction)

Aufbau principle

procedure in which the electron configuration of the elements is determined by “building” them in order of atomic numbers, adding one proton to the nucleus and one electron to the proper subshell at a time

blackbody

idealized perfect absorber of all incident electromagnetic radiation; such bodies emit electromagnetic radiation in characteristic continuous spectra called blackbody radiation

Bohr’s model of the hydrogen atom

structural model in which an electron moves around the nucleus only in circular orbits, each with a specific allowed radius

chalcogen

element in group 16

continuous spectrum

electromagnetic radiation given off in an unbroken series of wavelengths (e.g., white light from the sun)

core electron

electron in an atom that occupies the orbitals of the inner shells

covalent bond

attractive force between the nuclei of a molecule’s atoms and pairs of electrons between the atoms

covalent compound

(also, molecular compound) composed of molecules formed by atoms of two or more different elements

covalent radius

one-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond

d orbital

region of space with high electron density that is either four lobed or contains a dumbbell and torus shape; describes orbitals with ℓ = 2.

degenerate orbitals

orbitals that have the same energy

effective nuclear charge

charge that leads to the Coulomb force exerted by the nucleus on an electron, calculated as the nuclear charge minus shielding

electromagnetic radiation

energy transmitted by waves that have an electric-field component and a magnetic-field component

electromagnetic spectrum

range of energies that electromagnetic radiation can comprise, including radio, microwaves, infrared, visible, ultraviolet, X-rays, and gamma rays