DIVE ICP Definitions for Quarterly Exam 1

Atom

The smallest unit of elements, made up of electrons surrounding the nucleus of protons and neutrons.

element

A pure chemical substance made up of only one type of atom. It cannot be broken down into simpler substances, by normal scientific methods.

symbols

A shorthand notation for elements, made up of one or two letters from the element's name.

molecule

A group of two or more atoms that are covalently bonded together.

diatomic molecule

A molecule composed of two atoms bonded together.

compound

A substance made up of two or more elements chemically joined together.

molecular formula

Expresses how many atoms of each element that are in a chemical compound.

pure substances

A substance entirely composed of identical particles. An element is composed of identical atoms, while a compound is composed of identical molecules.

mixtures

Two or more pure substances that are mixed together, and not chemically bonded.

homogenous mixture

A mixture that has a uniform composition.

heterogeneous mixture

A mixture in which the different ingredients are identifiable.

colloids

A mixture in which one substance made up of very small particles is dispersed throughout another substance.

Tyndall effect

Light will not be dispersed when passing through a liquid or solution, but it will be dispersed by the particles suspended in a colloid or suspension.

suspension

A heterogeneous mixture, that differs from a solution in that it contains particles that are not permanently suspended, and will eventually settle out of.

Law of definite proportions

A compound is always composed of the same elements, in the same ratios. A compound's chemical formula does not change.

electrons

Particles that are smaller than protons or neutrons, they have a negative charge.

nucleus

The dense central area of an atom, where the protons and neutrons are located.

protons

Particles that carry a positive charge; the number of protons distinguishes one element from another.

neutrons

Particles that have a neutral charge.

energy levels

Together they make up the area of an atom containing the electrons, with each level containing electrons of a certain amount of energy.

quantum model

It describes electrons as existing in a cloud, with electrons in regions of probability called orbitals instead of separate and distinct energy levels.

orbitals

The area of an atom that an electron is most likely to be in, given its amount of energy.

Physical Property

Qualities of a substance that can be observed and measured without changing the identity of the substance.

Chemical Property

Qualities whose identification requires a change in the substance's structure. They describe how a substance will behave in a chemical reaction.

Chemical Change

Takes place in definite proportions, and results in the formation of new compounds and/or elements. It involves the breaking of bonds, and the formation of new ones.

Angstroms

A unit of distance equal to ten to the power of negative ten (10-10) meters.

Temperature

A measure of the average kinetic energy of the particles in a substance.

Absolute Zero

0 K on the Kelvin scale, it is the theoretical minimum possible temperature, at which an object would have the lowest possible kinetic energy.

Kelvin (K)

The basic unit of measurement on the Kelvin scale, which is the unit of measurement in the metric system.

Diffusion

When particles spread out to evenly fill a space.

Brownian movement

The random movement of particles in a liquid or gas.

Phases

The different states of matter, such as solids, liquids, or gasses.

Solids

A state of matter in which the object has a definite shape and volume.

Compressibility

The ability to reduce the volume of a substance.

Amorphous solid

A solid that is made up of atoms that have no particular organization.

Crystalline

Solids

A solid formed by particles that are arranged in an orderly repeating pattern.

Liquid

A state of matter which is characterized as having definite volume, but no definite shape.

Viscosity

The thickness of a liquid.

Gas

A state of matter in which the particles move about freely, with no structure. It will always fill the container it is in, assuming its size and shape.

Gas Pressure

The pressure caused by gas particles hitting the sides of the container surrounding them.

Plasma

A state of matter similar to gas, but in which the particles are moving at much greater speeds, and are electrically charged.

Melting

The process in which a solid changes phases into a liquid.

Melting Point

The temperature at which a substance transitions from a solid to a liquid.

Boiling

A phase transition in which a liquid rapidly changes to a gas.

Boiling Point

The temperature at which a liquid changes to gas.

Evaporation

The process in which a liquid changes phase into a gas. It only takes place at the surface of a liquid.

Condensation

A phase change in which a substance transitions from the gas phase, to the liquid phase.

Sublimation

The process in which a solid transitions directly into a gas, without becoming a liquid.

Freezing

The process in which a liquid undergoes a phase change to become a solid.

Freezing Point

The temperature at which a substance transitions from a liquid to a solid.

Accuracy

The degree of closeness between a measured value, and its actual value.

Precision

The degree of closeness of repeated measurements. How close the results of multiple trials of something are to each other.

Scientific Notation

A method of expressing extremely large or extremely small numbers, using powers of ten.

Significant digits

The number of digits known for certain, plus one estimated digit.

Mass

Usually used interchangeably with weight, because an object's mass and weight are proportional to each other. The quantity of inertia possessed by an object that can be multiplied by the acceleration due to gravity to determine its weight.

Balance

An instrument used to measure an object's mass.

Spring Scale

A device used to measure the weight of an object.

Law of Mass Conservation

Mass cannot be created or destroyed. For any amount of chemical or physical changes, total mass remains constant.

Weight

The force that gravity exerts on an object. It is the mass of an object multiplied by acceleration due to gravity.

Newtons (N)

The SI unit of force, or weight.

Meniscus

The curved surface of a liquid. It will be a convex curve if the liquid molecules have a greater attraction to themselves than the container, or a concave curve when the liquid molecules have a greater attraction to the container than each other.

Water Displacement Method

A method to determine the volume of an object. It is submerged in a graduated cylinder of water, and then the different in water level is used to determine the volume of the object.

Density

The mass per unit volume of a substance.

Units

Units of measure are letters that give meaning to a numerical value. They define the magnitude of a physical quantity.

Metric System

A system of measurement based on multiples of ten and the decimal. The base unit of measurement is the meter.

SI

System International, it is an internationally agreed upon system of measurement for mass, distance, and volume based on the metric system.

Unit Multiplier

A fraction made up of equivalent measures, that is equal to one. It is used to convert from one unit to another.

Unit Analysis

A method of converting between various units of measure.

Scientific Method

The systematic collection and classification of data, and usually the formulation and testing of a hypothesis based on that data.

Data

A collection of facts and information, which you may have recorded during an experiment, from which conclusions and decisions can be made.

Inductive Reasoning

Starts as facts and works towards general conclusions (science). It is the process of finding rules.

Deductive Reasoning

Starts with general statements and leads towards specifics. It is about applying rules.

Hypothesis

An educated guess, based on preliminary research and broad ideas, that can then be tested and verified, or not.

theory

It has been verified a number of times experimentally, and is stronger than a hypothesis, although not as strong as a law.

Law

An established principle or scientific generalization that is believed to be universally true.

Variables

Something that is changed, and is different in each experiment.

treatment

A variable in a scientific experiment.

Control

The standard in an experiment that whatever factors are being tested are not applied to.

Verify

To confirm the accuracy of something.

Observation

The act of receiving information through the senses, and recording it.

Science

A systematic study through careful observation, collection of data, and experimental investigation; observations of the physical universe.

Truth

Anything that is not false.

Pure Science

It is based on deductions from demonstrated facts and truths, but is not focused on practical applications; "the quest for knowledge".

Applied Science

Solving practical problems by the application of one or more fields of pure science.

Faith

Confidence or trust in something, that is not based on actual proof.

Bias

An inclination or predisposition in a certain direction that prevents an unprejudiced consideration of a question.

Fact

Something that actually exists, that has been observed or experienced.