8th Milestones Review

How is 'energy' defined in science?

The ability to change something.

According to the Law of Conservation of Energy, energy cannot be _____ or _____.

created; destroyed

What is a 'system' in a scientific context?

A way of thinking used to study how parts of matter and energy relate and interact.

In a closed system, what happens to the total amount of matter and energy?

It remains constant or is conserved.

What is the term for energy changing from one form to another within a system?

Transformation

Identify three forms of 'stored' energy.

Chemical energy, thermal energy, and energy in magnetic or electric fields.

What are the two defining characteristics of matter?

It has volume (takes up space) and mass (can be weighed).

The extraordinarily small particles that combine to make up matter are called _____ or _____.

atoms; molecules

List the four states of matter mentioned in the text.

Solid, liquid, gas, and plasma.

What determines the specific state or form of an amount of matter?

The way the particles making up the matter interact with each other.

Concept: Thermal Energy

Definition: The random motion of particles (vibrations in solids or free motion in gases).

In what direction does thermal energy always flow between objects of different temperatures?

From an object with a higher temperature to one with a lower temperature.

Term: Electrical Energy

Definition: The energy resulting from the motion of electrons along a path formed by a conductor.

What is 'light energy' a form of?

Electromagnetic radiation.

When rubbing hands together, friction transforms kinetic energy into which two other forms?

Heat energy and sound energy.

Term: Conduction

Definition: The movement of heat through an object or between objects that are in direct contact.

How is thermal energy transferred during conduction at the atomic level?

Through the collision of atoms.

Term: Convection

Definition: The movement of heat through fluids and gases via currents caused by density differences.

In convection, what happens to the density of a liquid as its thermal energy increases?

Its density decreases as molecules move faster and space farther apart.

Term: Radiation

Definition: The transfer of thermal energy through space via electromagnetic waves without requiring matter.

Which method of heat transfer is capable of moving through a vacuum?

Radiation

Concept: Force

Definition: An interaction between two objects, either in contact or at a distance from each other.

Identify three examples of contact forces.

Frictional force, tension force, and applied force.

Identify three examples of forces that act at a distance.

Gravitational force, electrical force, and magnetic force.

What two factors determine the amount of electrical force between two charged objects?

The magnitude of the charges and the distance between the objects.

How does decreasing the distance between two charged objects affect the electrical force?

It increases the electrical force.

In an electric field, what indicates a 'negative' charge?

A surplus of electrons.

What two factors determine the magnitude of magnetic force between two objects?

The magnetic strength of the objects and the distance between them.

How is an electromagnet created?

By using an electric current to produce a magnetic field in a coil of wire.

Identify three ways to make an electromagnet stronger.

Add an iron core, use more wire coils, or use a stronger electric current.

What is the process of generating an electric current by moving a magnet near a wire called?

Electromagnetic induction

A _____ is a device that converts mechanical energy into electrical energy.

generator

A _____ is a device that converts electrical energy into mechanical energy.

motor

Concept: Static Electricity

Definition: A phenomenon occurring when there is an imbalance between negative and positive charges in objects.

Why do maglev trains experience significantly less friction than standard trains?

They use magnets to float on a cushion of air, avoiding contact with solid tracks.

What is the smallest unit of matter that defines a chemical element?

The atom

Term: Element

Definition: A pure chemical substance made up of only one type of atom.

Term: Molecule

Definition: A particle made of two or more atoms joined together chemically.

Term: Substance

Definition: Matter that cannot be broken down by physical means but can be broken down using chemical changes.

Concept: Compound

Definition: A pure substance made of two or more different elements combined chemically.

Concept: Mixture

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

What distinguishes a heterogeneous mixture from a homogeneous mixture?

In a heterogeneous mixture, the parts are not evenly distributed.

Identify an example of a solid homogeneous mixture.

Bronze (a mixture of copper and tin).

According to the trend in thermal energy, which state of matter has the least thermal energy?

The solid phase.

A change in thermal energy in a material can cause a phase change or a _____ change.

temperature

Term: Physical Property

Definition: A measurable characteristic observable without changing the chemical identity of an object.

Term: Density

Definition: A physical property describing how tightly matter is packed together.

What is the boiling point of water in Celsius and Fahrenheit?

$100^{\circ}C$ ($212^{\circ}F$)

What is the melting point of water in Celsius and Fahrenheit?

$0^{\circ}C$ ($32^{\circ}F$)

Term: Chemical Property

Definition: A characteristic that can only be measured by chemically changing the identity of an object.

Concept: Combustibility

Definition: A chemical property describing how easily a substance will set on fire.

Concept: Reactivity

Definition: The capacity of an atom or molecule to undergo a chemical reaction with another substance.

How does a physical change differ from a chemical change regarding a substance's identity?

A physical change does not alter chemical properties, while a chemical change forms new substances.

Term: Precipitate

Definition: A solid that forms as the result of a chemical reaction, often within a solution.

How is the Periodic Table of Elements arranged?

By increasing atomic number (count of protons).

What are the common properties of Group 1 and Group 2 elements?

They are reactive solid metals rarely found in pure form.

Which group in the periodic table consists of highly unreactive gases?

Group 18

Identify the three kinds of particles that make up an atom.

Protons, neutrons, and electrons.

Concept: Proton

Definition: A positively charged particle found in the nucleus that identifies the type of element.

Concept: Neutron

Definition: A particle found in the nucleus that is neutral and has no electric charge.

Concept: Electron

Definition: A negatively charged particle, much lighter than protons, that moves outside the nucleus.

What defines a 'neutral' atom?

The number of positive protons and negative electrons are equal.

Term: Ion

Definition: An atom that has gained or lost electrons, resulting in a net electric charge.

If an atom loses an electron, what kind of charge does it acquire?

A positive charge.

If an atom gains an electron, what kind of charge does it acquire?

A negative charge.

What is the atomic number of Hydrogen?

1 (meaning it has one proton).

What is the atomic number of Oxygen?

8 (meaning it has eight protons).

What determines the fundamental characteristic and type of element an atom is?

The number of protons in the atom.

In the Periodic Table, in what directions does the mass of an atom generally increase?

From left to right and from top to bottom.

Which subatomic particle is the lightest?

The electron.

The _____ is the name for the motion of electrons along a path formed by a conductor.

electricity

What is the primary difference between plasma and gas?

Plasma is a high-energy state of matter that is charged and conducts electricity easily.

Concept: Volume

Definition: The amount of space that an object or substance occupies.

How are particles arranged and moving in a solid?

They are packed tightly together and vibrate in place but do not move around easily.

How do particles move in a liquid compared to a gas?

Liquid particles move around and are packed loosely, while gas particles are spread far apart and move in all directions.

Identify an example of a chemical change involving vinegar and baking soda.

The formation of bubbling foam (a gas).

Is dissolving salt in water a physical or chemical change?

A physical change (salt is still present if water evaporates).

Group 17 elements on the Periodic Table are highly reactive _____ and _____.

gases; liquids

Which pure substance is made of two atoms of oxygen combined?

An oxygen molecule ($O_{2}$).

What occurs when a balloon is rubbed with wool to create static electricity?

Electrons are stripped from the wool due to friction and collect on the balloon.