Science Exam

Convert 1,685 cm to meters

16.85 m

Safe laboratory procedures

Goggles, aprons,no horseplay, waft to smell, no food or water, tie hair back

What is a system of knowledge and the methods used to find that knowledge?

ScienceA factor in an experiment that changes from the manipulation of the independent vairable is the _________.

A factor in an experiment that changes from the manipulation of the independent vairable is the _________.

Dependent Variable

An experiment was designed to investigate the effect of caffeine on the heartbeat of Daphnia. Two populations of Daphnia were cultured. Both populations had water and the same mineral content, were supplied with identical amounts of bacteria as food, received the same amount of light, and had their temperature maintained at 20 degrees. Every two hours, Daphnia from both populations were selected, and their heartbeats were monitored. The Daphnia of population one had caffeine administered 5 minutes before their heartbeat was checked. The Daphnia of population 2 were given nothing.

Dependent Variable: __________

Independent Variable: ___________

Control: __________

Constant: ______________

1. Heartbeat Rate

2. Caffiene

3. Population 2 (no caffiene)

4. Same mineral content, same amount of food, same amount of light, same temperature, same amount of time between when heartbeats are checked

If a racecar driver drives his car around a track for 500 laps and the starting and ending line are at the same place his distance is greater than/less than his displacement.

Greater than

The product of an object’s ______ and ________ is its momentum.

mass

velocity

3 ways an object can accelerate

Slows down

Speeds up

Changes direction

A horizontal line on a distance-time graph means the object is _______

at rest

Acceleration is the rate of change of _____.

Velocity

5 m/s south is an example of ______.

Velocity

_______ is a change in position.

Motion

Why would a real car moving at 20 km/h have more momentum that a toy car moving at the same speed?

The real car has more mass.

When an unbalanced/balanced force acts on an object, the object accelerates.

Unbalanced

Number value of acceleration due to gravity is _________.

9.8 m/s²

Which of Newton’s Laws states the following: “to every action there is an equal and opposite reaction”.

3

What force keeps the Moon in orbit around Earth?

Gravity

The greater an object’s _____, the greater the object’s inertia.

mass

Formula for Newton’s 2nd Law

F=ma

The forces acting on a falling feather would be _______ and __________.

gravity

air resistance

SI unit for force

Newton

SI unit for energy

Joules

SI unit for power

Watts

According to the law of conservation of energy, the total; amount of energy in the universe ________________.

remains constant

Work transfers _________.

energy

Kinetic energy is the energy of ________.

motion

The rate at which work is done is called ____.

power

A device that does work with only one movement and changes the size of direction of a force

simple machine

True or False: A force acting on an object does no work if the force is not in the direction of the object’s motion.

True

______ is the transfer of thermal energy from one object to another because of a difference in temperature.

Heat

True of False: Metals conduct heat.

True

Energy from the Sun travels to Earth as _______.

Radiation

As the temperature of an object rises, so does the _______ energy of the object.

thermal

Units used for temperature

Kelvin, Celcius, Farenheit

If you move a substance from one container to another and its volume changes the substance is a ___.

gas

During a phase change the temperature of a substance ___________________________.

stays the same

True or False: Most of the circuits in your home are series circuits.

False

Electric charge that has accumulated on an object is referred to as ______ ___________.

Static electricity

A material through which electrons do not easily flow is an __________.

insulator

If an object gains electrons it becomes ___________ charged

negatively

True or False: If you put a negatively charged object and a positively charged object near each other, they would repel each other.

False

SI unit for resistance

Ohms

Electromagnetic radiation with the shortest wavelength are ___________.

gamma rays

A wave will travel only as long it has _______ to carry.

energy

Waves in which the particles of the medium move only in the same direction of motion of the wave are ____________ waves.

compressional

The color ________ is produced by blending three primary colors of light.

white

You can see this paper, your desk, and the person in front of you because light is being ________.

reflected

Two examples of pure substances

Elements

Compounds

Examples of physical changes

Cutting wood or hair

(Change in color, shape, size, density, melting point, boiling point)

State of matter with a definite volume, but no a definite shape

Liquid

State of matter where volume can change if the container it is in changes

GasD

State of matter where the atoms are tightly held together

Solid

Most common state of matter in the universe

Plasma

Characteristics of mixtures

Varying properties or compositions

Evidence of a chemical change

Bubble formation, formation of a precipitate, odor

Dot diagrams represent ___________________.

valence electrons

As you move from left to right across a period, the number of valence electrons ___________.

increases

Location of a positive charge in an atom

Nucleus

Number unique to every element

Atomic Number

Reactivity of an element is closely related to its __________________.

electron configuration

Calculate mass number

protons + neutrons

Characteristics of nonmetals

Usually gases

Brittle Solids

Poor Conductors

Location of metalloids

Stairsteps

Chemical symbols represent the _____ of an element.

name

Rows are called _________.

periods

Columns are called _________.

groups

Examples of elements with stable electron configuration

Neon, helium, argon (noble gases)

Why atoms gain or lose electons

Atoms bond to fill their outer shells to become stable

How ionic bonds form

Transfer of electrons

Formation of diatomic molecules

Two atoms of the same nonmetals that react

Sharing of electrons in polar covalent bonds is ___________.

unequally

Elements most likely to form more than one type of ion

Transition metals

Number of each element in a chemical formula

Subscripts

Shows what elements a compound contains and the exact numbers of atoms of those elements

Chemical Formula

Chemical equation with the same number of atoms of each element on both sides of the equation

Balanced chemical equation

Atoms of the reactants unbond, rearrange, and then rebound to form the products

Chemical reaction

Count the atoms: (NH4)2 CR2 O7

N=2

H=8

Cr=2

O=7

19

Can count by subscripts

States that the mass of all substances present before a chemical change equals the mass of all the substances remaining after the change

Law of conservation of mass

Result of the strong force not being able to hold the nucleus together

Nuclear Decay

What nucleus stability depends on

Ratios protons and neutrons

Causes of chain reactions

Neutrons hitting other nuclei

Type of chemical reaction when heat must be added

Endothermic reaction

Type of chemical reaction when two or more substances combine to form another substance

Synthesis reaction

Substance that speeds up a chemical reaction

Catalyst

Acid Ions

H+

Base ions

OH-

Organic compounds that change color in acids and bases

Indicator

Where chemical energy is stored within a compound

Bonds

Type of chemical reaction when a substance is broken down into two or more simpler substances.

Decompistion reaction

Measures how acidic or basic a substance is that ranges from 0-14

pH

Penetrating power of nuclear radiation

Weakest: Alpha rays

Strongest: Gamma rays

True or False: Nuclear Decay rates vary with the conditions of the reaction, but chemical reaction rates do not.

False

Amount of time it takes for half the nuclei in a sample of a radioactive isotope to decay

Half-life

How stars including the sun produce energy

Nuclear Fusion

Unit used to measure distance to stars

light years

What spectral lines identify

Lines that tell you the different elements

First type of fuel that stars use

hydrogen

4 properties astronomers used to classify stars

Color

Temperature

Size

Brightness

Forces that are in balance with stars

Gravity

Apparent Brightness

A star’s brightness as seen from a certain location

Close = bright

Far = dim