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8th Grade Science > Final Study Guide > Flashcards

Final Study Guide Flashcards

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1
Q

What is an isotope?

A

Atoms of the same element that have different numbers of neutrons

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2
Q

An isotope of Boron-10 has 5 protons. Another isotope, Boron-11 would have ______ protons, ______ neutrons, and _______ electrons

A

5,6,5

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3
Q

A fluorine atom has 9 protons, 10 neutrons, and 9 electrons. An isotope of fluorine would have a different number of _________________

A

Neutrons

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4
Q

What was Dalton’s atomic theory?

A

All matter is made up of atoms, Atoms cannot be created, divided, or destroyed, All atoms of certain elements are identical but different from atoms of other elements, Atoms join with other atoms to make new substances

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5
Q

What does the atomic number of an atom represent?

A

The atomic number represents the number of protons in an atom

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6
Q

Why is hydrogen in group one and why is it like the halogens?

A

Hydrogen has only 1 valence electron like group 1. Hydrogen is like the halogen because it only needs one additional electron to complete its outer level

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7
Q

What are valence electrons and why are they important?

A

Valence electrons are the electrons in the outermost energy level. They tell us the element’s reactivity.

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8
Q

How many valence electrons do atoms in groups 1, 2, 13, 14, 15, 16, 17, and 18 have?

A

Groups 1 & 2 - the # of valence electrons is the same as the group number; Groups 13-18 - the # of valence electrons is the group number minus 10.

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9
Q

Why do atoms in group 18 not react in nature?

A

They have a full outermost energy level.

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10
Q

How is helium different from the other noble gases in group 18?

A

Helium has two valence electrons in its first and only energy level.

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11
Q

Elements in the same ________ (vertical column) have similar properties.

A

Group

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12
Q

What group of elements are Halogens most likely to combine with?

A

Group 1 since Halogens have 7 valence electrons and need only one more to be full.

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13
Q

What is the law of conservation of mass?

A

States that matter is neither created nor destroyed in ordinary physical and chemical changes.

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14
Q

What does the law of conservation of mass have to do with balancing equations?

A

When balancing chemical equations the reactants and products must contain the same number of atoms of each element.

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15
Q

What group of elements are the most reactive? Least reactive?

A

Most - group 1 Alkali metals are the most reactive because they only have one valence electron and it is easily taken. Least - Noble gasses are the least reactive because they have a full outer energy level and need no more electrons to be stable.

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16
Q

What side of the periodic table easily gains electrons? Lose electrons?

A

Groups 1 and 2 lose electrons and groups 15, 16, and 17 gain electrons.

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17
Q

What are the characteristics of metals?

A

Shiny, conducts heat and electricity well, most solid at room temperature, many are malleable, some are ductile

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18
Q

What are the characteristics of nonmetals?

A

Poor conductors of heat and electricity, often dull and brittle

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19
Q

What type of compound forms when a metal bonds with a nonmetal?

A

Ionic

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20
Q

What type of compound forms between two nonmetals?

A

Covalent

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21
Q

When a transfer of electrons takes place between a metal and a nonmetal, the metal
and nonmetals become _______ because they have gained or lost electrons.

A

Ions

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22
Q

If an element has 3 valence electrons, what group is it in? What will its charge be when it reacts to form an ion?

A

Group 13; 3+

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23
Q

What is the definition of an organic compound? What element will all organic compounds contain?

A

A covalent compound composed of carbon-based molecules; they must contain carbon and hydrogen; and can contain oxygen, nitrogen, phosphorus, and silicon.

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24
Q

What is a chemical reaction?

A

The process in which atoms are rearranged to produce new substances; the bonds that hold atoms together may be formed or broken.

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25
Q

What are the 5 signs that a chemical reaction is taking place?

A

color change, odor change, precipitate formation, gas formation, energy change

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26
Q

What is a subscript?

A

numbers written below and to the right of chemical symbols; tell you how many of each type of atom are in a molecule.

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27
Q

How many elements are in the chemical formula NaOH? How many atoms are in this formula?

A

Elements - 3; Atoms - 3

28
Q

What is a coefficient?

A

A number is placed in front of a chemical formula; it tells the number of molecules of a specific compound.

29
Q

How many atoms of each element are in 2HC^2H^3O^2?

A

H - 8, C - 4, O - 4

30
Q

What are inhibitors and catalysts?

A

Inhibitors - a substance that slows down or stops a chemical reaction; Catalysts - a substance that speeds up the rate of a chemical reaction.

31
Q

What are some examples of chemical reactions?

A

Leaves changing colors, striking a match, using a battery, taking a photograph with a film camera

32
Q

What is an exothermic reaction?

A

Exothermic - a chemical reaction in which energy is released to the surroundings - energy is given off in several forms (light, heat, sound, etc)

33
Q

What is an endothermic reaction?

A

Endothermic - a chemical reaction that requires an input of energy - energy is taken in during the reaction.

34
Q

What is the difference between an atom and an element?

A

An atom is the smallest particle into which an element can be divided and still be the same substance; smallest unit of an element that has all the properties of that element.

35
Q

On what side of the arrow would you find the reactants?

A

left

36
Q

On what side of the arrow would you find the products?

A

right

37
Q

What is plate tectonics?

A

States that Earth’s surface is made up of giant, moving slabs called tectonic plates

38
Q

What are the 3 pieces of evidence that support the theory of plate tectonics?

A

similar fossil evidence, shapes of continents, location of earthquakes and volcanoes (Sea-floor spreading, magnetic reversals, also support the theory)

39
Q

Describe how the 3 types of plate boundaries form.

A

Convergent- a boundary in which two plates are coming together. There are 3 types, O-O, C-O, and C-C. Divergent- a boundary in which two plates pull away from each other. Transform- a boundary in which two plates are sliding horizontally past each other

40
Q

Describe how the following are formed: folded mountains, fault-block mountains, volcanic mountains, subduction zones, mid-ocean ridges, trenches, and rift valleys.

A

olded mountain- at a convergent boundary where two plates push together, Fault-block mountains- Where large pieces of rock break due to tension at divergent boundaries, Volcanic mountains- When plates collide and one plate subducts under another, allowing magma to push up to the surface. Also at divergent boundaries at mid-ocean ridges, Subduction zone- at oceanic-oceanic or continental-oceanic convergent boundaries. The denser plate subducts, or goes under the less dense plate, Mid-Ocean Ridge- These are found at divergent boundaries where the crust is pulled apart and sea-floor spreading is happening, Trenches- are found at subduction zones as one plate goes under another, Rift Valleys- are formed by divergent boundaries where the crust is pulled apart forming shallow valleys

41
Q

Why was Alfred Wegener’s Theory of Continental Drift not accepted by the scientific community?

A

He could not give an explanation as to why the continents moved, only that he thought they had

42
Q

What areas of Earth would you find earthquakes?

A

Wherever you find plate boundaries

43
Q

What is sea-floor spreading and what type of boundary would you find here?

A

Seafloor spreading is where new sea floor forms, pushing existing rock in opposite directions. You would find a mid-ocean ridge at a divergent boundary

44
Q

What did sea-floor spreading provide an explanation for?

A

Provided explanation for continental drift

45
Q

What is erosion and give an example of a formation formed by erosion found in the US?

A

Erosion transports rock, sediment, and soil from one place to another: The Great Lakes (glacier), Grand Canyon (water)

46
Q

What is weathering?

A

The process by which rock is broken down into smaller particles

47
Q

How does a river over time, weather the land, and what feature will this eventually form?

A

The river will erode away the land and eventually form a canyon

48
Q

Be able to identify landforms on satellite maps such as canyons, rivers, and alluvial fans.

A

Go study

49
Q

A swimmer swims the 400 m freestyle in 2.5 minutes with a force of 50 Newtons. How much work did he do?

A

W=FxD W= 50N x 400m W= 2000 Joules

50
Q

If 2 vehicles are moving with a force of 100 N, which vehicle would have the most acceleration, the car or the 18-wheeler?

A

the car, because it has less mass

51
Q

When a person skydives from an airplane, they fall until the upward force of air resistance on their parachute becomes equal to the downward force of gravity. When these two forces become equal in magnitude, what happens to the skydivers speed?

A

It will stay constant.

52
Q

Which of Newton’s laws explains how the rocket moves when launched?

A

Newton’s 3rd law states that for every action there is an equal and opposite reaction. The gas and flame pushing down and away from the rocket propels the rocket up.

53
Q

What is important to remember when first focusing a microscope?

A

Use the coarse adjustment knob first

54
Q

What is the function and location of each of the following parts of a microscope? Illuminator, objective lens, stage, eyepiece, coarse focus

A

Illuminator - light source, directs light through stage and specimen
objective lens- lenses of different magnifications
stage- supports the slide and allows light to pass through
eyepiece- contains the ocular lens (10x magnification)
coarse focus- moves the stage up and down

55
Q

A windmill sits quietly and still until it is hit by a gust of wind and begins turning. Explain how this is an example of Newton’s first Law of Motion.

A

Newton’s First Law states that an object in motion will remain in motion and an object at rest will remain at rest unless acted on by an unbalanced force. The windmill stays still until acted on by the unbalanced force of the wind.

56
Q

Two forces of 6N and 3N act upon an object in opposite directions. What is the new combined (net) force and direction of movement?

A

6N-3N = 3N left

57
Q

Fire Energy Transformation

A

Chemical potential energy
- Heat and light energy

58
Q

Radio Energy Transformation

A

Electrical energy
- Sound energy

59
Q

Dynamite Energy Transformation

A

Chemical potential energy
- Heat and light energy

60
Q

Waterfall Energy Transformation

A

Gravitational potential energy
- Kinetic and sound energy

61
Q

Person drinking milk energy transformation

A

Chemical potential energy
- Heat and kinetic energy

62
Q

What does an experimental Investigation have?

A

an independent and dependent variable

63
Q

Once a conclusion is reached in a scientific investigation, is that scientific area of study always complete? Why or why not?

A

No, the conclusion can be used to determine what to do next

64
Q

What do you need to develop a hypothesis?

A

A hypothesis can be developed after making observations or based on previous experiments. Must be testable.

65
Q

List the steps of the scientific method in logical order

A

Ask well-defined questions
Form a testable Hypothesis and make predictions
Plan an investigation (Identify variables)
Collect & organize data by testing the hypothesis in an experiment
Interpret data and analyze information
Draw and defend conclusions

66
Q

What does it mean if your hypothesis does not match your results? If a scientific investigation results in an unexpected conclusion, was it a waste of time? Why or Why not?

A

It means that your prediction wasn’t supported or proven by the results. This is not a waste of time. This can lead scientists to develop a new hypothesis to test in additional experiments, leading to new discoveries.

67
Q

In a laboratory investigation, what is a control group? An experimental group? How many testing variables (independent variables) should be included?

A

A control group does not receive the treatment and is the source of comparison. An experimental group receives the treatment (independent variable). There should only be one tested independent variable in an investigation.

8th Grade Science (1 decks)

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