GED Science Flashcards

Question

Molecules and Bonds

Answer 1

When elements combine to form molecules or ionic compounds, their constituents are held together by bonds. There are two main types of bonds: - Covalent - atoms share a pair of electrons, each atom contributing one electron (water) - Ionic - atoms gain or lose electrons to become ions, and the attraction between positively and negatively charged ions holds the compound together (sodium chloride NaCl, i.e. table salt)

Answer 2

Matter is anything that has mass and takes up space. The mass of an object is the amount of matter that it contains, and its weight is a measure of the gravitational force exerted on it. The mass of an object never changes, but its weight can change.

Answer 3

Solids have a definite shape and volume because the molecules of which they are made occupy fixed positions and do not move freely. In some solids, such as minerals, the molecules form an orderly pattern called a crystal. Liquids have a definite volume but no definite shape. A liquid conforms to the shape of its container. Gases have no definite shape or volume. The states of matter can be changed by adding or removing heat energy. The temperature at which a solid becomes a liquid is its melting point. The temperature at which a liquid becomes a gas is called its boiling point. The temperature at which a gas becomes a liquid is its condensation point. The temperature at which a liquid becomes a solid is its freezing point. Water is the only substance that is found naturally in all three states on Earth.

Answer 4

A solution is a mixture (such as salt water) that is uniform throughout and that contains ions, atoms, or molecules of two or more substances. The substance in a solution that is dissolved is called the solute. The substance in which the solute is dissolved is the solvent. Water is called the universal solvent because so many substances dissolve in it. Solutions are not always liquid. They can be solids, as when two or more metals are combined in an alloy, or they can be gases, as when oxygen and nitrogen are combined in the air.

Answer 5

The mass of the products always equals the mass of the reactants (the law of conservation of mass). Chemical reactions are either endothermic (absorb energy) or exothermic (energy is given off with the products, usually in the form of heat or light). Activation energy is the amount of energy needed to get a reaction going.

Answer 6

An acid is a compound that releases hydrogen ions (H+), or protons, in the presence of water. Strong acids are corrosive. A base is a compound that accepts hydrogen ions, or protons. When an acid reacts with a base, the product is a salt and water. This reaction is called neutralization.

Answer 7

Energy is the capacity to do work. Work is done whenever a force is applied to an object to set it in motion. Thus, anything that can force matter to move, change direction, or change speed has energy. Energy comes in many forms: - Heat - Light - Electrical - Chemical - Nuclear - Mechanical - Sound Energy can be converted from one form to another. The law of conservation of energy - energy can neither be created nor destroyed, only changed in form. Two basic types of energy are potential and kinetic. Potential energy is the energy of position. Kinetic energy is the energy of motion.

Answer 8

Work done is measured in joules. The rate of doing work or consuming energy is called power, and it is measured in horsepower (in the English system) or watts (joules per second in the metric system).

Answer 9

E = mc2 E is energy m is mass c is the speed of light

Answer 10

Speed is the rate at which an object moves. Velocity is speed in a given direction. Acceleration is the rate at which velocity changes.

Answer 11

Is anything that changes the state of rest or motion of an object.

Answer 12

The first law of motion, the law of inertia - an object at rest will stay at rest until a force acts upon it, and an object in motion will stay in motion at a constant speed in a straight line until a force acts upon it. The second law of motion, the law of motion or acceleration - the acceleration of an object depends on its mass and the force acting upon it. The greater the force, the greater the acceleration. The more massive the object, the more force it takes to accelerate it. If a constant force acts upon an object, the object will move with constant acceleration in the direction of the force. The third law of motion - for every action, there is an equal and opposite reaction. This law was used to derive the law of conservation of momentum. Momentum is related to the amount of energy that a moving object has, and it depends on the mass of the object and its velocity (object's mass multiplied by its velocity). When an object is given a certain amount of momentum in a particular direction, some other object must receive an equal momentum in the opposite direction. All forces exist in pairs, all forces are interactions between objects.

Answer 13

Sometimes electrons are temporarily pulled away from atoms, creating stationary areas of positive and negative charge. This can happen when two objects, like a balloon and a rug, are rubbed together, creating static electricity.

Answer 14

The movement of charged particles through a substance, usually electrons, is an electric current. Direct current flows in one direction only and is used in battery-operated devices. Alternating current flows back and forth rapidly and is used in household wiring. A material that allows electrons to move freely from atom to atom is called a conductor (metals). A material that does not allow electrons to move freely from atom to atom is called an insulator (rubber and plastic). Semiconductors are substances whose ability to conduct electricity is midway (silicon is used in electronic devices).

Answer 15

An electric current produces a magnetic field that affects magnetic substances such as iron in the same way a permanent magnet does. Magnetic fields are produces by moving charged particles. In an electromagnet, the charged particles move along a coil of wire connected to a battery or other power source. In a permanent magnet, the spinning of electrons creates a magnetic field.

Answer 16

Is a complete pathway for the flow of electric current. It consists of a source of electricity, such as a battery, wires along which the current travels, devices called resistors powered by the current, and often a switch to start and stop the flow of current. To have current, you need to have a loop. Any break in the loop will stop current.

Answer 17

Just as an electric current produces a magnetic field, a moving magnetic field produces an electric current. This principle underlies electric motors, generators, and transformers. In an electric motor, magnetic fields are produced by electric currents. The magnetic fields push against one another, turning the shaft of the motor. In a generator, a moving magnetic field produces electric current. In a transformer, an incoming electric current in coiled wire produces fluctuating magnetic fields, which in turn produce an outgoing electric current of a different voltage. The difference in voltage is caused by the differing sizes of the wire coils.

Answer 18

Three main layers: (1) the crust - consists of rocks, 5 to 64 km (2) the mantle - consists of silica and metal-rich minerals, 2900 km (3) the core - has two layers: the outer core (mostly liquid iron) and the inner core (mostly solid iron). Extreme heat and pressure characterize the core.

Answer 19

Earth's crust is made up of tectonic plates that fit together like a crude jigsaw puzzle. These plates move relative to one another at a rate of up to 15 cm (6 in) a year. At the boundaries between plates, major landforms such as mountain ranges, volcanoes, ocean trenches, and mid-ocean ridges form, and earthquakes occur. Three types of plate boundaries, or margins: (1) Constructive margin - two plates are moving apart and new crust is forming. Molten material from the mantle below wells up in the space between the plates, hardens, and forms new crust, usually at a mid-ocean ridge. (2) Destructive margin - two plates colliding and crust is being destroyed. When a continental plate collides with an oceanic plate, the denser oceanic crust may be forced under the other plate, forming a deep trench. When two plates consisting of continental crust collide, the crust crumples to form mountain ranges. (3) A transform, or conservative, margin - two plates are sliding by one another, and no crust is created or destroyed.

Answer 20

Include air, water, soil, minerals, and energy. Less than 3% of the world's water is fresh water. Energy resources include fossil fuels, flowing water, wind, solar energy, and geothermal energy.

Answer 21

Those whose supply will not run out, either because there is an unlimited supply (solar), or because the resource cycles through the environment (water). Renewal energy resources, in addition to solar, include the water power of flowing rivers, tidal and wave power from the movement of ocean water, wind power from the movement of air, and geothermal power from the heat in the Earth's crust.

Answer 22

Weather is the day-to-day change in conditions in the atmosphere at a particular place on Earth. Climate is the average weather conditions of a large region over a long period of time. All weather and climate ultimately arise from the uneven heating of the Earth. The sun's rays fall more directly at the equator than they do at the poles. This resulting uneven heating causes global wind circulation patterns: the warm air at the equator rises, creating an area of low pressure, and moves toward the poles. Cold air at the poles sinks, creating an area of high pressure, and moves toward the equator. This creates a pattern of prevailing winds in both hemispheres. Another major influence on weather and climate is the worldwide pattern of ocean currents. Ocean currents are caused by the wind and by variations in the density of water (warm water is less dense than cold water). Ocean currents help transfer heat from the equatorial regions to the poles.

Answer 23

Caused by the movement of air masses, large bodies of air with similar temperature, humidity, and pressure. The boundary between two air masses is called a front. A cold front occurs where a cold air mass overtakes and displaces a warm air mass. A warm front occurs where a warm air mass rises over a cold air mass. An occluded front occurs when a cold front catches up with a warm front and the two weather systems merge. Clouds and precipitation are characteristic of fronts.

Answer 24

Troposphere - 0 to 6 miles Stratosphere - 6 to 31 miles Mesosphere and ionosphere - 31 to 50 miles Thermosphere - 50 to 435 miles Exosphere - 800 to 3000 km

Answer 25

Acidic and alkaine (or "basic") are two extremes that describe substances, usually liquids or chemicals. A substance that is neither acidic nor alkaline is neutral. The pH scale measures how acidic or alkaline a substance is. The scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic. Pure water is neutral, with a pH of 7.0. When chemicals are mixed with water, the mixture can become some level of either acidic or alkaline. Vinegar and lemon juice are acidic substances, while laundry detergents and ammonia are alkaline.

Answer 26

Are responsible for the conversion of one molecule into another, but they are not changed or used up.

Answer 27

Fnet = m x a Fnet is force m is mass a is acceleration

Answer 28

p = m x v p is momentum m is mass v is velocity