Chemistry Midterm

Science

An organized way of gathering and analyzing evidence about the natural world.

Chemistry

The study of the properties of matter and how matter changes

Chemical

any substance that has a definite composition

Mass

the amount of matter in an object

Matter

Anything that has mass and takes up space

Atom

a basic unit of matter that cannot be broken down by normal chemical reactions

Element

A pure substance made of only one kind of atom

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds

chemical symbol

one or two letters that represent an element

Energy

the ability to do work

kinetic energy

energy of motion

potential energy

stored energy

thermal energy

Heat energy

chemical potential energy

Energy stored in chemical bonds

System

A group of parts that work together as a whole

Surrounding

everything outside the system

extensive property

a property that depends on the amount of matter in a sample

intensive property

a property that depends on the type of matter in a sample, not the amount of matter

physical property

a quality or condition of a substance that can be observed or measured without changing the substance's composition

physical change

A change in a substance that does not involve a change in the identity of the substance

change of state

the change of a substance from one physical state to another

Solid

Definite shape and volume

liquid

A state of matter that has no definite shape but has a definite volume.

Gas

A state of matter with no definite shape or volume

Plasma

Liquid part of blood

chemical property

A characteristic of a pure substance that describes its ability to change into different substances

chemical change

A change in matter that produces one or more new substances

chemical reaction

the process by which one or more substances change to produce one or more different substances

Reactant

A chemical substance that is present at the start of a chemical reaction

Product

A substance produced in a chemical reaction

Mixture

A combination of two or more substances that are not chemically combined

Homogeneous

of the same kind

Solution

A homogeneous mixture of two or more substances

Heterogeneous

composed of different kinds, diverse

pure substance

A sample of matter, either a single element or a single compound, that has definite chemical and physical properties

Group

A column on the periodic table

Family

vertical column of elements in the periodic table; elements in a family all have similar chemical properties; also called a group

Period

A horizontal row of elements in the periodic table

metal

an element that is shiny and that conducts heat and electricity well

Nonmetals

Elements that are poor conductors of heat and electric current

Metalloids

Elements that have properties of both metals and nonmetals.

Scientific Method

A series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.

System

A group of parts that work together as a whole

Hypothesis

A testable prediction, often implied by a theory

Model

A representation of an object or event

Theory

A hypothesis that has been tested with a significant amount of data

quantity

amount

SI

International System of Units

Weight

A measure of the force of gravity on an object

Derived Unit

A unit defined by a combination of base units

Volume

The amount of space an object takes up

Density

mass/volume

Conversion factor

a ratio of equivalent measurements

dimensional analysis

a technique of problem-solving that uses the units that are part of a measurement to help solve the problem

Accuracy

how close a measurement is to the true value

Precision

a measure of how close a series of measurements are to one another

percentage

A ratio that compares a number to 100

error

mistake

sig figs

All the digits that can be known precisely in a measurement, plus a last estimated digit

scientific notation

A method of writing or displaying numbers in terms of a decimal number between 1 and 10 multiplied by a power of 10.

directly proportional

a term used to describe the relationship between two variables whose graph is a straight line passing through the point (0,0)

inversely proportional

A term used to describe the relationship between two variables whose product is constant.

Proton

positively charged particle

Neutron

no charge

Electron

negatively charged particle

Nucleus

Control center of the cell

Isotopes law of conservation of mass

for any system closed to all transfers of matter and energy (both of which have mass), the mass of the system must remain constant over time.

law of definite proportions

a given compound always contains exactly the same proportion of elements by mass

Law of Multiple Proportions

if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers

Atom

Basic unit of matter

Nuclear forces

the interaction that binds protons and neutrons, protons and protons, and neutrons and neutrons together in a nucleus

atomic number

the number of protons in the nucleus of an atom

Isotopes

Atoms of the same element that have different numbers of neutrons

mass number

the total number of protons and neutrons in a nucleus.

Nuclide

a general term for a specific isotope of an element

unified atomic mass unit

exactly 1/12 the mass of a carbon-12 atom

average atomic mass

weighted average of the atomic masses for the isotopes of an element

Mole

the SI base unit used to measure the amount of a substance

Avogadro's number

number of representative particles in a mole, 6.02 X 10^23

molar mass

the mass of one mole of a pure substance

periodic table

A table that shows the elements, their atomic number, symbol, and average atomic mass; elements with similar chemical properties are grouped together.

Atomic emission spectrum

the set of frequencies of the electromagnetic waves emitted by atoms of the element

Energy levels

the fixed energies an electron can have

Quantum

the amount of energy needed to move an electron from one energy level to another

Quantum mechanical model

the modern description of the behavior of electrons in atoms

Atomic model

The smallest unit of an element, consists of protons and neutrons in a nucleus orbited by a number of electrons

Electromagnetic radiation

The energy transferred through space by electromagnetic waves.

Electron magnetic spectrum

All of the frequencies or wavelengths of electromagnetic radiation

Wavelength

The distance between two corresponding parts of a wave

Frequency

the number of complete wavelengths that pass a point in a given time

Photoelectric effect

refers to the emission of electrons from a metal when light shines on the metal

Photon

A particle of electromagnetic radiation with no mass that carries a quantum of energy

Ground state

The lowest energy state of an atom

Excited state

when an atom absorbs energy, its electrons move to a higher energy level

Line emission spectrum

A series of specific wavelengths of emitted light created when the visible portion of light from excited atoms is shined through a prism

Continuous spectrum

an emission spectrum that consists of a continuum of wavelengths.

Heisenberg uncertainty principle

it is impossible to know exactly both the velocity and the position of a particle at the same time

Quantum theory

the theory that describes matter and energy at very small (atomic) sizes

Orbital

Quantum number

the number assigned to each orbit of an electron