Kategorier: Alle - elements - nucleus - compounds - evolution

af Kyler Owenby 5 måneder siden

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Physical Science

The concept of matter encompasses everything that constitutes the universe, with all substances being composed of atoms. The atomic theory has evolved significantly since its inception by Greek philosopher Democritus in 440 B.

Physical Science

Forces decrease when the distance between the interacting objects increases.

Physical Science

Energy

Electricity and Magnetism
Electromagnetism- a magnetism resulting from electric charge in motion
Magnet- any material that attracts iron. All magnets have two poles- a negative and positive pole. These poles are where the magnetic forces are the strongest.

A magnetic field is a region around a magnet that is affected by magnetic forces.

Electric circuits- a path that electricity flows through. A closed circuit has no breaks in it, an open circuit has a break.

Parts of a circuit

Switch- opens and closes a circuit by bringing together or seperating two pieces of metal.

Wires- used to connect the energy source(s) to the load(s).

Load- a device that the electric circuit is delivering the electrical current to. Example; light bulb.

Energy source- a battery with a negative and positive charged terminal.

Current Electricity is a continuous flow of electric charge

Alternating current(AC) is current in which the electric charges flow in one direction, then in the reverse direction, over and over again.

Direct current(DC) electricity is current in which the electric charge moves in one direction. Example; Batteries

Static Electricity- the build up of electric charge on an object by rubbing. Example; rubbing a balloon on your hair.

The sudden and brief flow of electrons is called static discharge. Example; touching someone and feeling a small zap, lightning.

Laws of electric charges.

The attractive or repulsive force between charged objects is called electric force. The strength of electric force between charged objects depends on the size of the charge and distnace between them.

Like charges repel +> <+ -> <- Unlike charges attract +< >-

Waves- an oscillation that travels from one place to another with a certain velocity.
Characteristics of waves

Wave speed- the distance a wave travels in a given amount of time.

Frequency- the number of oscillations produced in a certain amount of time. Frequency is measure in hertz(Hz)

Wavelength- the distance from any point on one wave to a corresponding point on an adjacent wave.

Amplitude- the distance a wave oscillates from its restion position.

Electromagnetic waves are waves that can travel through empty spaces. Examples; visible light, x-rays, radio waves.
Mechanical waves are waves that travel through matter. Examples; sound waves, water waves.
Forms of Energy
Nuclear Energy

The energy contained in the nuclei of atoms

Chemical Energy

The energy stored in chemical bonds

Electrical Energy

The energy produced by electric charges

Sound Energy

The energy carried by sound waves

Light Energy

The energy carried by light and other kinds of electromagnetic waves

Thermal Energy

The energy related to the temperature of an object

Potential Energy

The energy an object has because of its position of shape

Kinetic Energy

The energy an object has because it is moving

Mechanical Energy

The energy an object has because of its motion or position

Forces and Motion

Machines
Pulley

A wheel with a rope or chain attached. the wheel rotates around a fixed axle and the rope rides the groove of the wheel making it easier to lift heavy or awkward objects.

Wheel and Axle

An axle is inserted through the middle of a wheel. Any force applied the wheel gets transferred to the axle and vice versa.

Lever

A long rigid bar that rests on and pivots around a support.

There are 3 types of levers, first-class, second-class, and third-class. The classification is in regard to the location of the fulcrum

Screw

A long cyndrilacal piece of metal that holds two materials or objects together.

Wedge

An inclined plane that moves to fulfill its purpose. Example, axe or door wedge

Inclined Plane

A flat surface that slopes to make an incline. This simple machine does not move. Example, ramp for wheel chair accessibility

Motion
Newton's Laws of Motion

Newton's Third Law of Motion

When two objects interact, they apply forces to each other of equal magnitude and opposite direction.

Newton's Second Law of Motion

The force of an object is equal to its mass times acceleration

Newtons's First Law of Motion

An object will not change its motion unless a force acts upon it

Force- a push or pull on an object.
Balanced and Unbalanced Forces

Unbalanced force produces change in the motion of an object

Balanced force produces no change in the motion of an object

Friction- the force that opposes motion between two surfaces that are in contact with each other. It could prevent motion from starting or oppose motion in progress.
Magentic Force- associated with moving electric charges.

Magnet- any material that attracts iron.

Electric Force- associated with unmoving charges.

Positive and negative charge attracts, positive and positive or negative and negative repels.

Gravity- the force of attraction between objects that have mass

The strength of gravity depends on the mass of the objects and the distance between them.

The closer together the objects, the stronger the gravitational force.

Mass- a measure of the amount of "stuff" in an object. The greater the mass of either object, the stronger the gravity between them.

Matter- the "stuff" that all objects and substances in the univers are made of.

Elements, Molecules and Compounds
Compounds- elements that are found in combination with other elements.

Example: Water is 2 Hyrdogen and 1 oxygen. H20

Molecules- the combination of two or more atoms.

Diatomic Molecules- a molecule that only contains 2 atoms

Elements are the simplest form of matter. There are 110 known elements in the universe.
Atoms
Evolution of Atomic Theory

Greek Philosopher Democritus proposed the existence of atoms in 440 B.C.

British Chemist John Dalton proposed that all substances were made of atoms- small, hard dense spheres that could not be created, destroyed, or altered.

British Scientist J.J. Thompson proposed that atoms themselves were made up of smaller particles. He discovered that atoms contained negatively charged particles.

Ernest Rutherford proposed that atoms had a dense, positively charged nucleus surrounded by electrons in 1911.

In 1913, Danish Scientist Niels Bohr furthered the theory by suggesting electrons revolved around the nuclues in circular paths, called orbit.

The current model is known as the electron cloud model, electrons surround the nucleus, traveling in regions called clouds.

Atomic Structure

Electrons- Negatively charged particles found outside the nucleus of an atom.

Isotopes- atoms of the same element that have different numbers of neutrons.

Neutrons- Located in the nucleus, electrically neutral.

Protons- Positively charged particles loacted in the nucleus

Nucleus- the center of the atom where protons and neutrons stick together.

The smallest particle into which an element can be divided and still maintain the properties of that element.
States of Matter
Gas

Can flow

Takes on the shape and volume of its container

Liquid

Keeps the same volume, in a container or not

Takes on the shape of the container

Solid

Keeps its shape and volume

Physical properties of matter
Solubility- The ability to dissolve in another substance.
Electrical Conductivity- how well a substance allows electricity to flow through it
Melting Point- the termperature at which a substance turns from a solid to a liquid.
Boiling Point- the temperature at which a substance changes from a liquid to a gas.
Malleability- the ability to be pressed or pounded into a thin sheet.
Ductility- the ability to be pulled inot a thin strand, like a wire.
Density- The amount of matter in a given volume(mass per unit volume)