8th Grade Midterm Study Set (Chapters 1-5)

goggles

protects eyes from chemical splashes

fire extinguisher

A device that sprays chemicals that put out fires.

gloves

personal protective equipment used to protect skin on hands from harmful germs

eye wash station

used to wash chemicals from your eyes

first aid kit

A set of tools that you use for a simple medical treatment that is given as soon as possible.

Scientific Method

A logical, systematic approach to the solution of a scientific problem

experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process

Hypothesis

A testable prediction, often implied by a theory

Observation

the action or process of observing something or someone carefully or in order to gain information.

Conclusion

A summary based on evidence or facts

analysis

The process or result of identifying the parts of a whole and their relationships to one another.

controlled variable

a factor in an experiment that remains constant

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied.

dependent variable

The measurable effect, outcome, or response in which the research is interested.

Theory

well-tested explanation that unifies a broad range of observations

law

a descriptive statement or equation that reliably predicts events under certain conditions

Data

Facts, figures, and other evidence gathered through observations.

Quantitative

Data that is in numbers

Qualitative

relating to, measuring, or measured by the quality of something rather than its quantity. (Opinions)

Repetition of an experiment _.

doing the same experiment over and over again by the same person.

Replication in an experiment

Redoing an experiment from another scientist

bar graph

a graph that uses vertical or horizontal bars to show comparisons among two or more items

circle graph

A data display that uses pieces of a circle to show parts of a whole

line graph

A graph that uses line segments to show changes that occur over time

DRY MIX

Dependent variable, Responding, Y-axis, Manipulated variable, Independent variable, X-axis

x-axis

the horizontal line on a graph

y-axis

the vertical line on a graph

Graphs must have

Title, X-Axis and Y-Axis labels, units, if needed, Key, if needed

data table

Any display of information in tabular form, with rows and/or columns named.

SI units

a system of physical units ( SI Units ) based on the meter, kilogram, second, ampere, kelvin, candela, and mole, together with a set of prefixes to indicate multiplication or division by a power of ten.

metric system

The decimal measuring system based on the meter, liter, and gram as units of length, capacity, and weight or mass.

graduated cylinder

instrument used to measure volume of a liquid

thermometer

An instrument used to measure temperature

meter stick

tool used to measure length

triple beam balance

instrument used to measure mass

SI unit for mass

kilogram (kg)

SI unit for temperature

Kelvin (K)

SI unit for length

meter (m)

SI unit for time

second (s)

SI unit for volume

cubic meter (m^3) or liter (L) or millimeter (mL)

Accuracy

how close a measurement is to the true value

Precision

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

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

Subscript

A number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound

Coefficient

A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.

Atom

Basic unit of matter

Molecule

A group of atoms bonded together

Reactant

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

product

A substance produced in a chemical reaction

yields

Makes, creates, produces; Arrow in chemical equation

Law of Conservation of Mass

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

octet rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

noble gases

the elements in Group 8A of the periodic table

ionic bond

A chemical bond resulting from the attraction between oppositely charged ions. (typically between a metal and a nonmetal)

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule (typically two nonmetals)

Atoms

Basic unit of matter

Electrons

negatively charged subatomic particles

Protons

Positively charged particles

Neutrons

the particles of the nucleus that have no charge

valence electrons

Electrons on the outermost energy level of an atom

atomic number

number of protons

atomic mass

Number of protons and neutrons

metals on periodic table

elements on the left side of the periodic table

nonmetals on the periodic table

right of staircase

Metalloids

Elements that have properties of both metals and nonmetals.

periods on periodic table

horizontal rows

groups on periodic table

vertical columns

energy shells

The orbital paths of electrons found at varying distances from the nucleus

Most reactive elements

Group 1(Alkali Metals)

least reactive elements

Group 18 (noble gases) are stable

Elements

A molecule composed of one kind of atom; cannot be broken into simpler units by chemical reactions.

Compounds

2 or more elements chemically combined

Mixture

material composed of two or more elements or compounds that are physically mixed together but not chemically combined

Mendeleev

Created the first periodic table. Arranged elements by increasing atomic mass

Bohr Model

model of an atom that shows electrons in circular orbits around the nucleus

Lewis Dot Structure

diagram of a molecule using dots to represent valence electrons

balanced forces

Equal forces acting on an object in opposite directions

unbalanced forces

forces acting on an object that combine and form a net force that is not zero

net force

The sum of all forces acting on an object

speed graph

Distance is located on y axis and time is located on x axis

Velocity

Speed in a given direction

Acceleration

The rate at which velocity changes

acceleration graph

Speed is located on the y axis and time is located on the x axis

Formula for speed

distance/time

formula for acceleration

final velocity-initial velocity/time

work

force x distance

units for work

Joules (J)

Power

the rate at which work is done

units for power

Watts (W)

Force

A push or a pull

Units for force

Newtons

Newton's First Law

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Newton's Second Law

Force = mass x acceleration

Newton's 3rd Law

For every action force there is an equal and opposite reaction force

formula for power

P=W/t

units for speed

m/s

units for acceleration

m/s squared

Units for velocity

m/s and direction

Inertia

The tendency of an object to resist a change in motion