Science 8th Grade Midterm

Ionization Energy

The energy required to remove an electron from a neutral atom

Electronegativity

The ability of an atom to attract electrons

Ion

An atom that has gained or lost electrons

Octet Rule

Atoms tending to gain, lose, or share electrons in order to have a full valence shell of 8 electrons

Chemical Bond

The attractive force between atoms that binds them together as a unit, having one of these will decrease the potential energy of these atoms and increase their stability

Ionic Bond

This forms between a metal and a non metal that become ions due to the transfer of electrons

Characteristics of atoms in an ionic bond

Conduct electricity, dissolve in water, form crystals, and have increased melting points

Covalent Bond

Bond formed by the sharing of electron pairs

Characteristics of atoms in a covalent bond

Will NOT conduct electricity, dissolve in water, form crystals, and will have decreased melting points. These will also be odorous.

Non-polar Covalent Bond

When two atoms share electrons equally

Polar Covalent Bonds

When electrons are shared, but not equally

Up and to the Right

The ionization energy and electronegativity of an atom increases going _____, meaning non-metals have more of these qualities because they are the “takers”

Bigger atoms

It is easier to take electrons from _____ because their valence electrons are farther from the nucleus

Ionic

The greater the difference in electronegativity between atoms, the more ____ the bond becomes

Subscript

a small number written to the right and slightly below a chemical symbol to indicate the number of atoms of that element present in a molecule or compound

Oxidation State

the hypothetical charge an atom would have when involved in an ionic bond

Cation

Atom with a positive oxidation state

Anion

Atom with a negative oxidation state

Polyatomic Ions

A group of covalently bonded atoms that act as a single ion

Dipole

A region of positive and negative charge in a molecule or formula unit

Chemical Formula

A shorthand representation of a substance using the the symbols for the atoms as well as subscript to indicate the number of each ato

Democritus

Stated the idea that all matter is made of tiny, indestructible, things called atoms

Ernest Ruthorford

Stated the idea that most of an atoms mass is in its tiny nucleus, and the rest is mainly empty space

John Dalton

Revolutionized our knowlege of atoms with his four part theory

Dalton’s Four Part Theory

1. All matter is composed of atoms. 2. Atoms of a given element are identical in mass and properties. 3. Atoms cannot be subdivided, created, or destroyed. 4. Atoms of different elements combine or be rearranged to form chemical reactions.

Dimitri Mendeleev

Came up with the original periodic table based on atomic mass rather than atomic numbers like the one today

JJ Thomson

Discovered that electrons make up atoms, made the plum pudding diagram

Plum Pudding Model

Chemistry

The study of matter and its interactions with other matter

Atoms

The basic units of matter, consisting of a nucleus surrounded by electrons. They determine the chemical properties of elements.

Elements

Pure structures that cannot be broken down further by chemical means

Protons

These make up an atoms nucleus and have a positive charge

Neutrons

These make up an atoms nucleus and have a neutral charge

Electrons

Subatomic particles that have a negative charge and orbit the nucleus of an atom.

Atomic Number

The number of protons (and electrons) in an atom's nucleus, which determines the chemical element and its properties. These organize our periodic table

Atomic Mass

The mass of an atoms nucleus, determined by the # of protons + neutrons, this organized Mendeleev’s periodic table

Electron Clouds

The area where electrons orbit the nucleus of an atom

Orbital

A region in an atom where there is a high probability of finding electrons.

Isotopes

Atoms of the same element with different numbers of protons (resulting in different atomic mass)

Average Atomic Mass

What you get when you average the masses of all isotopes of an element

amu

(atomic mass unit), standard unit of mass used to measure atomic weight

Atomic Number

Avg. Mass Number

Length

The distance between two points, also called height, distance, or width

Mass

The amount of matter in an object

Volume

The amount of space an object takes up

Storin’ and Pourin’

Purpose of a Beaker

Measuring the Volume of Liquid

Purpose of a Graduated Cylinder

Derived Unit

2 or more simple units combined

Density

Mass over Volume

Kelvin

SI unit for Temperature

Second

SI unit for time

Meter

SI unit for length

Gram

SI unit for mass

Liter

SI unit for volume

Meniscus

The middle of the curve at the top of a liquid in a graduated cylinder

100 degrees

Temperature at which water boils (Celcius)

0 degrees

Temperature at which water freezes (Celcius)

Accuracy

Getting close to the right answer

Presicion

Consistently getting a specific answer

Line Graphs

Can show relationships where the DV changes due to changes in the IV, often shows changes over time

X axis

Horizontal axis, always the IV

Y axis

Vertical Axis, always the DV

Solubility Curve

Shows how much of a substance will dissolve in 100 mL of water at a given temp

Bar Graph

Good for comparing multiple things and info gathered by counting

Pie Chart

Used to show how a fixed quantity is broken up, shows percentages

The motion of molecules

What is the Kelvin System Based on?

Hypothesis

An educated guess / a possible answer

A hypothesis proven to be true by a lot of evidence

Theory

Independent Variable

The variable that can be changed by the controller of the experiment

Dependent Variable

The variable that is measured in an experiment

Constant Variables

The variables that are kept consistent to achieve accurate results

Energy

the ability to do work

Kinetic Energy

The energy of motion

Potential Energy

Stored energy

Concentration

The number of something in a specific area

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Shorthand for concentration

Kinetic Molecular Theory

All matter is in constant, random motion. Motion is dependent on temperature. The higher the temp the faster the motion. The lower the temp the slower the motion until absolute zero is reached and all motion stops.

Absolute Zero

The hypothetical temperature when all motion of particles stops. (0 degrees Kelvin)

KE + PE

Thermal Energy formula

2nd Law of Thermodynamics

Particles will flow in random but constant motion to a high concentration to a low one until and equilibrium is reached (DIFFUSION)

Heat Transfer Methods

Conduction, Convection, Radiation

Heat

When Thermal Energy flows

Conduction

the transfer of heat through the direct contact of particles

Convection

The transfer of heat through fluids by the movement of heated particles

Radiation

The transfer of heat through electromagnetic waves of light

Cp

Specific Heat shorthand

Specific Heat

the amount of energy it takes to raise the temp of 1 kg of a substance by 1 degree kelvin

Jouls

Unit of measurement for specific heat

Solid

State of matter with definite volume and definite shape

Liquid

State of matter with definite volume and indefinite shape

Gas

State of matter with indefinite volume and indefinite shape

Melting

Phase change from a solid to a liquid

Freezing

Phase change from liquid to solid

Evaporation

Phase change from liquid to gas

Condensation

Phase change from gas to liquid

Sublimation

Phase change from solid to gas

Deposition

Phase change from gas to solid

Heat of Vaporization

The energy required for matter to turn from a liquid to a gas

Heat of Fusion

The energy required for matter to turn from solid to a liquid