Chemistry Semester 1 Exam

chemistry

The study of the properties of matter and how matter changes

substance

mass

the amount of matter in an object

matter

anything that takes up space and has mass

qualitative data

Information describing color, odor, shape, or some other physical characteristic

quantitative data

numerical data

scientific method

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

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied (x-axis)

dependent variable

The outcome factor; the variable that may change in response to manipulations of the independent variable (y-axis)

control

standard for comparison

model

an object, diagram, or computer program that helps us understand something by making it simpler or easier to see

theory

an explanation using an integrated set of principles that organizes observations and predicts behaviors or events

scientific law

A statement that describes what scientists expect to happen every time under a particular set of conditions

base unit

a defined unit in a system of measurement that is based on an object or event in the physical world

second

SI base unit for time

meter

SI base unit for length

kilogram

SI unit for mass

derived unit

a unit that is defined by a combination of base units

liter

Basic unit of volume in the metric system

cubic centimeter

a metric unit of volume equal to one-thousandth of a liter (cm³)

density

kilograms per meter cubed (kg/m³) or grams per centimeter cubed (g/cm³)

kelvin

SI unit for temperature

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.

conversion factor

a ratio of equivalent measurements used to convert a quantity from one unit to another

dimensional analysis

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

accuracy

A description of how close a measurement is to the true value of the quantity measured.

precision

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

percent error

the absolute value of the error divided by the accepted value, multiplied by 100

significant figures

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

physical property

A characteristic of a pure substance that can be observed without changing it into another substance

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

chemical property

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

solid

A state of matter that has a definite shape and a definite 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

vapor

the gas state of a substance that is normally a solid or a liquid at room temperature

states of matter

the physical forms of matter, which include solid, liquid, and gas

melting

solid to liquid

freezing

liquid to solid

vaporization

Liquid to gas

condensation

Gas to liquid

sublimation

solid to gas

deposition

gas to solid

physical change

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

chemical change

A change in matter that produces one or more new substances

phase change

a transition of matter from one state to another

reactant

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

product

A substance produced in a chemical reaction

law of conservation of mass

the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

mixture

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

homogeneous mixture

A mixture in which substances are evenly distributed throughout the mixture

solution

A homogeneous mixture of two or more substances

heterogeneous mixture

A mixture in which different materials can be distinguished easily

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

periodic table

A chart of the elements showing the repeating pattern of their properties

period

A horizontal row of elements in the periodic table

group

a vertical column of elements in the periodic table

law of definite proportions

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

percent by mass

mass of solute/mass of solution x 100

Dalton's atomic theory

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

atom

Basic unit of matter

cathode

Negative electrode

anode

Positive electrode

subatomic

smaller than an atom

electron

negatively charged particle

plum pudding model

J.J Thomson's model of an atom, in which he thought electrons were randomly distributed within a positively charged cloud

nucleus

Center of an atom

proton

positively charged particle

atomic number

the number of protons in the nucleus of an atom

chemical name

The name that describes the chemical composition and molecular structure of a drug.

atomic mass

The average mass of all the isotopes of an element

isotope

Atoms of the same element that have different numbers of neutrons

nuclear reaction

A reaction that involves a change in the nucleus of an atom

chemical reactions

the making and breaking of chemical bonds, leading to changes in the composition of matter

radioactivity

The process in which some substances spontaneously emit radiation

radiation

Energy that is radiated or transmitted in the form of rays or waves or particles.

radioactive decay

The breakdown of a radioactive element, releasing particles and energy

alpha radiation

Radiation that is deflected toward a negatively charged plate when radiation from a radioactive source is directed between two electrically charged plates

alpha particle

A cluster of 2 protons and 2 neutrons emitted from a nucleus in one type of radioactivity

beta radiation

Radiation that is deflected toward a positively charged plate when radiation from a radioactive source is directed between two electrically charged plates

beta particle

a high-speed electron or positron emitted in the decay of a radioactive isotope

gamma radiation

electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength

electromagnetic radiation

a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields vary simultaneously.

wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

photon

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

Planck's constant

6.626 x 10^-34 Js

frequency

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

hertz

the unit of frequency, equal to one cycle per second

amplitude

the height of a wave's crest

electromagnetic spectrum

the range of wavelengths or frequencies over which electromagnetic radiation extends.

atomic emission spectrum

the pattern formed when light passes through a prism or diffraction grating to separate it into the different frequencies of light it contains

Heisenberg uncertainty principle

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

principal quantum number

symbolized by n, indicates the main energy level occupied by the electron

principal energy levels

the major energy levels of an atom

ground state

the lowest allowable energy state of an atom

atomic orbital

a region of space in which there is a high probability of finding an electron

electron configuration

the arrangement of electrons in the orbitals of an atom

valence electrons

Electrons on the outermost energy level of an atom