8 th Grade Science Preview

Directions: Read the entire packet. Sketch and Label the 23 figures/diagrams only. Sketches are: Structure of an atom, elements/molecules/compounds, heterogeneous mixtures vs homogenous mixtures, weight vs. mass, states of matter, changes in states of matter, ionic vs covalent bonds, physical vs chemical change, endothermic vs exothermic reactions, kinetic vs potential energy, temperature scales, transverse and longitudinal waves, crest/trough/amplitude/wavelength, transparent/translucent/opaque, unbalances vs balanced forces, types of friction, Newton’s first law of motion, Newton’s second law of motion, Newton’s third law of motion, magnetic field lines, electric circuit, series vs parallel, and direct vs alternating current.

I. Structure and Properties of Matter (25 points)A. Chemistry is the study of properties of matter and how it changesB. Physics is the study of matter and energy and how they interactC. Matter is anything that has mass and occupies spaceD. Atom- the basic particle from which all elements are madeE. Structure of an atom

F. Atomic Number- number of protons in the nucleus of an atomG. Isotope- an atom with the same number of protons and a different number of

neutrons from other atoms of the same elementH. Mass number- the sum of the protons and neutrons in the nucleus of an atomI. Periodic Table of Elements- a chart of the elements showing the repeating pattern

of their propertiesJ. Period- the horizontal row of the elements on the periodic tableK. Group- the vertical column of the periodic table, also called the familyL. Chemical symbol- one or two letter representation of an element

M. Elements, Molecules, and Compounds

N. Mixture- two or more substances that are mixed together but not chemically bonded

O. Heterogeneous mixture vs homogeneous mixture

P. Solution forms when substances dissolve into other substancesQ. Weight (measure of force of gravity on an object) vs Mass (amount of matter in

an object)

R. Volume- amount of space that matter occupiesS. Density- how much mass of a substance is contained in a given volume

T. States of Matter

U. Surface Tension- result of an inward pull among the molecules of a liquid that brings the molecules on the surface closer together; causes the surface to act as if it has a thin skin

V. Viscosity- a liquid’s resistance to flowingW. Changes in States of Matter

X. Metal- a class of elements characterized by physical properties that includes shininess, malleability (can be pounded into shapes), ductility (can be pulled out into a long wire), and conductivity (ability to transfer heat or electricity to another object)- example: iron

Y. Corrosion- the gradual wearing a way of a metal element due to a chemical reaction

Z. Nonmetal- an element that lacks most of the properties of a metal- example: oxygen

AA. Metalloid- an element that has characteristics of metals and nonmetals- example- silicone

BB. Nuclear Fusion- process in which two atomic nuclei combine to form a larger nucleus, forming a heavier element and releasing huge amounts of energy

CC. Particle accelerator- a machine that moves atomic nuclei at higher and higher speeds until they crash into one another, sometimes resulting in nuclear fusion

II. Interactions of Matter (15 points)A. Valence electron- electrons that are at the highest energy level of an atom (in the

outer orbit) and are involved in chemical reactionsB. Chemical bond- the force that holds two atoms togetherC. Ion- an electrically charges atomD. Ionic vs covalent bonds

E. Polar bond- covalent bond in which electrons are shared unequallyF. Nonpolar bond- covalent bond in which electrons are shared equallyG. Alloy- mixture of two or more elements, in which one of the elements is a metalH. Physical property- characteristic of a pure substance that can be observed

without changing it into another substance (Example: color, viscosity)I. Chemical Property- characteristic of a pure substance that describes its ability to

change into a different substance (Example: burning, reactivity with water)

J. Physical vs Chemical Change

K. Endothermic vs exothermic reaction

L. Chemical reaction- process in which substances undergo chemical changes that result in the formation of a new substance

M. Precipitate- a solid that forms from a solution during a chemical reactionN. Reactant- a substance that enters into a chemical reactionO. Product- a substance formed as a result of a chemical reactionP. Conservation of Mass- principle stating that mater is not created nor destroyed

during a chemical reactionQ. Catalyst- material that increases the rate of a reactionR. Inhibitor- a material that decreases the rate of a reaction

III. Energy (15 points)A. Energy is the ability to do work or cause change

B. Kinetic vs. Potential Energy

C. Gravitational potential energy- potential energy that depends on the height of an object

D. Elastic potential energy- the energy of starched or compressed objectsE. Mechanical energy- kinetic or potential energy associated with the motion or

position of an objectF. Thermal energy- total energy of all the particles of an objectG. Temperature- measure of the average energy of motion of the particles of a

substanceH. Temperature Scales

I. Absolute zero- temperature at which no more energy can be removed from matter

J. Heat- thermal energy that is transferred from matter at a higher temperature to matter at a lower temperature

K. Electrical, chemical, nuclear, electromagnetic energyL. Energy transformation- process of changing from one form of energy to anotherM. Law of conservation of energy- energy cannot be created nor destroyed, it can

only change formsIV. Light and Sound (15 points)

A. Wave- disturbance that transfers energy from one place to anotherB. Medium- material through which a wave travelsC. Mechanical wave- wave that requires a medium through which to travelD. Transverse and Longitudinal Waves

E. Vibration- repeated back and forth or up and down motionF. Crest, Trough, amplitude, and wavelength

G. Frequency- the number of complete waves that pass a given point in a certain amount of time

H. Hertz (Hz)- Unit of measurement for frequencyI. Reflection- bouncing back of an object or a wave when it hits a surface through

which it cannot passJ. Refraction- the bending of waves as they enter a new medium at an angleK. Seismic wave- wave produced by an EarthquakeL. Echo- reflected sound wave

M. Transparent, Translucent, Opaque

V. Force and Motion (15 points)A. Motion- state in which one object’s distance from another is changingB. Reference point- a place or object used for comparison to determine if an object

is in motionC. Speed- the distance an object travels per unit of timeD. Average speed- overall rate of speed at which an object moves- calculated by

dividing the total distance an object travels by the total timeE. Instantaneous speed- speed of an object at one instant of timeF. Velocity- speed in a given directionG. Acceleration- rate at which velocity changesH. Force- a push or a pull exerted on an objectI. Net force- the overall force on an object when all the individual forces acting on it

are added togetherJ. Unbalanced vs balanced forces

K. Friction- force that one surface exerts on another when the two surfaces rub against each other

L. Types of friction

M. Gravity- the force that pulls objects toward each otherN. Free fall- the motion of a falling object when the only force acting on it is gravityO. Air resistance- fluid friction experienced by objects falling through airP. Terminal velocity- the greatest velocity a falling object can achieveQ. Projectile- an object that is thrownR. Inertia- tendency of an object to resist any change in motionS. Momentum- product of an object’s mass and velocityT. Law of conservation of momentum- rule that states in the absence of outside

forces the total momentum of objects that interact does not changeU. Newton’s First Law of Motion

V. Newton’s Second Law of Motion

W. Newton’s Third Law of Motion- Every action has an equal and opposite reaction

VI. Electricity and Magnetism (15 points)A. Magnet- any material that attracts iron and materials that contain ironB. Magnetic pole- ends of a magnetic object, where magnetic field is strongestC. Magnetic force- force produced when magnetic poles interactD. Magnetic field- the region around a magnet where the magnetic force is exertedE. Magnetic field lines- invisible lines that map out the magnetic field around a

magnet

F. Electric Force- attraction or repulsion between electric chargesG. Electric Field- the region around a charged object where the object’s electric force

interacts with other charged objectsH. Static Electricity- buildup of charges on an objectI. Conservation of charge- the law that states that charges are neither created nor

destroyed buy only transferred from one material to anotherJ. Electric current- continuous flow of electric charges through a material

K. Electric circuit- complete, unbroken path through which electric charges can flow

L. Voltage- difference in electrical potential energy between two places in a circuitM. Resistance- measure of how difficult it is for charges to flow through a materialN. Series vs parallel circuit

O. Direct current- current consisting of charges that flow in only one direction in a circuit

P. Alternating current- current consisting of charges that move back and forth in a circuit

Q. Direct vs alternating current