DC Chemistry Chapter 1-4 Exam - Emma Vosika

Pure Research

A type of research used to gain knowledge, for the sake of knowledge itself

Applied Research

A type of research used to solve a specific problem

Model

Something that represents an idea, event, or object to help people better understand it. (Too big, too little, too difficult to understand.)

Bias

Something that occurs when someone's expectations change how the results are analyzed or the conclusions are made

Independent Variable

The variable that changes to see what will happen

The independent variable is also known as:

The manipulated variable

Dependent Variable

The variable that is measured to find its effect

The dependent variable is also known as:

The responding variable

Control Variable

The variable that stays the same for all trials

The control variable is also known as:

The constant

A scientific theory

An explanation of things or events based on investigations

A scientific law

A statement about what happens in nature and that seems to be true all of the time

Precision

A measure of how close a series of measurements are to one another

Accuracy

A measure of how close a measurement comes to the actual or true value of whatever is measured

Quantitative

Results that can be measured and described with numbers

Qualitative

Results that are described in words. Results of our five senses: (Sight, smell, taste, hear, touch)

Mass

A measurement that reflects the amount of matter

Weight

A measurement of Earth's gravitational pull on matter

Substance

AKA: A chemical. Matter that has a definite and uniform composition.

Pure Substance

Matter that has a definite or fixed composition

Element

The simplest type of pure substance: composed of one type of atom

Compound

A pure substance that is composed of two or more elements that are chemically combined in a fixed proportion

Mixtures

Two or more different substances that are physically mixed BUT not chemically combined

Hetergeneous Mixture

A mixture in which the components do not have a uniform composition

Homogeneous Mixture

A mixture in which the composition is uniform throughout

Chemical Property

Properties that describe the ability of a substance to change into a new substance

Physical Property

A characteristic of matter that can be observed or measured without changing the sample's composition

Intensive Property

A property that DOES NOT depend on the amount of material

Extensive Property

A property that DOES depend on the amount of material

Physical Change

A change that only affects physical properties, but the substance remains the same

Chemical Change

A change that causes the substance to change into one or more new substances

Gas to Solid

Deposition

Solid to Gas

Sublimation

Solid to Liquid

Melting

Liquid to Solid

Freezing

Liquid to Gas

Evaporation

Gas to Liquid

Condensation

Law of Conservation

Mass is neither created nor destroyed in a chemical reaction; it is conserved

Accepted Value

The correct/true value

Experimental

The value measure in a lab

Percent Error

A measure of accuracy in a lab

Percent Error Equation

((Experimental-Accepted) *100)/Accepted

Density

A ratio of mass to volume

Energy

The capacity to do work

Law of Conservation of Energy

Energy is not created nor destroyed, only converted from one form to another

Specific Heat

The amount of energy required to raise 1 g of a substance by 1C

Law of Conservation of Matter

When a chemical reaction takes place, matter is neither created nor destroyed

Law of Constant Composition

(AKA Law of Definite Proportions): Multiple samples of any pure chemical compound always contain the same percent by mass of each element making up the compound

Atomic Number

The number of protons in an element (When an element is neutral, there are the same # of electrons as protons)

Mass Number

The number of protons and neutrons in the nucleus of an atom

Isotopes

Atoms of the same element that have different numbers of neutrons

Atomic Mass

The weighted average mass of all naturally occurring isotopes

Law of Mendeleev

Properties of the element recur in regular cycles (periodically) when elements are arranged in order of increasing atomic mass (This repeating pattern is known as chemical peridocity)

Ion

An atom or molecule with a net electric charge

Cation

Positive ion

Anion

Negative ions

First Ionization Energy

The minimum amount of energy required to completely remove an electron from a neutral atom

Wavelength

The distance between two equal and adjacent points on a wave

Frequency

The number of waves that pass a point in a certain amount of time

Photons

Packets of light energy

Classical Physics

1. Says that objects can have any energy

2. Works well for large objects (things that humans can measure, like a tennis ball, a car, a planet)

Quantum Physics

1. Says that objects can have any energy

2. Works well for large objects (things that humans can measure, like a tennis ball, a a car, a planet)

3. Objects can only have particular energies

4. Generally used for VERY small things (an electron)

Ground State

The lowest possible energy for a [articular electron (stable)

Excited State

A temporary amount of energy that an electron can hold for a short amount of time

Sublevels

Locations in which electrons with identical energy are found

Orbital

A three dimensional volume in which electrons have the highest probability of being found

Pauli Exclusion Principle

Orbitals can only hold two electrons and they must have opposite spins

Aufbau Principle

Fill the lowest energy first

Hund's Rule

Each orbital in a subshell must hold one electron before any orbital, in that subshell, can only two electrons

Electron configuration

The way electrons are arranged in orbitals around the nucleus

Atomic Size

(AKA Atomic Radius): Half the distance between two nuclei of adjacent atoms

Ionization Energy

The energy needed to remove one electron from an atom in the gaseous state

Electronegativity

A measure of the ability of an atom t o take an electron from another atom