8th Grade Chemistry

Chemistry Idk

Matter

What everything is composed of

Atom

The simplest particle of an element

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge

Cohesion

an attraction between molecules of the same substance

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid

Element

A pure substance that cannot be broken down chemically into simple kinds of matter

A compound

What is a pure substance made up of two or more elements?

A molecule

_________ is the simplest part of a substance that still has all of the properties of that substance.

Valence Electron

Electrons on the outermost energy level of an atom

energy level

a region of an atom in which electrons of the same energy are likely to be found

Mixture

A combination of two or more substances that are not chemically combined

homogenous mixture (solution)

a mixture that is the same in its properties throughout given samples

heterogeneous mixture

A mixture that is not the same in composition; components are not evenly distributed throughout the mixture

Solution

What is a mixture where 2 or more substances are uniformly distributed in another substance?

Solute

___________ is the substance dissolved in the solution.

Solvent

___________ is the substance in which the solute is dissolved

Water

What is the universal solvent?

Filtration

A process that separates materials based on the size of their particles.

Sifting

a process used to separate the parts of a mixture by particle size

Periodic Table

an arrangement of elements in which the elements are separated into groups based on a set of repeating properties

Chemical Symbol

A one or two letter representation of an element

Number of protons

What is the atomic number of an element?

Atomic mass

What do you find by adding the number of protons and neutrons together?

Period

A horizontal row of elements in the periodic table

Group

Vertical column in the periodic table

Reactivity

How readily a substance combines chemically with other substances.

Metals

Elements that are good conductors of electric current and heat.

Non-Metals

Low conductivity, not ductile, not malleable, brittle, dull, gas at room temp

Mettalloids

elements with some of the properties of metals and some of the properties of non-metals. Found along the zig zag line

Alkali Metals (Group 1)

Group 1 on the periodic table.
1) Soft metals
2) Reacts quickly with oxygen
3) Reacts violently with water
4) Most reactive group on Periodic Table

Alkaline Earth Metals (Group 2)

metallic elements in group 2 of the periodic table which are harder than the group 1 alkali metals but also less reactive than

Transition Metals (Groups 3-12)

Good thermal conductors, shiny, electric conductors, higher density and melting points than group 1+2, 1-2 valence electrons

Halogens (Group 17)

Very reactive non-metals. Atoms of this group have seven electrons in their outer level. Also known for forming salts.

Noble Gases (Group 18)

Elements in group 18 that have a full 8 electrons in the outer energy shell and, therefore, are stable and tend not to form chemical bonds. Least reactive elements on Periodic Table

Chemical Formula

A combination of chemical symbols and numbers to represent a substance

Subscript

A number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound

Coefficient

A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.

The Yield of a Chemical Reaction is how much you actually made

Chemical Property

A characteristic of a pure substance that describes its ability to change into different substances

Physical Property

A characteristic of a pure substance that can be observed without changing it into another substance

Chemical Change

A change in matter that produces one or more new substances

Physical Change

A change in a substance that does not involve a change in the identity of the substance

catalyst

substance that speeds up the rate of a chemical reaction

Reactant

A chemical substance that is present at the start of a chemical reaction

Product

A substance produced in a chemical reaction

Concentration

A measurement of how much solute exists within a certain volume of solvent

pH Scale

scale with values from 0 to 14, used to measure the concentration of H+ ions in a solution; a pH of 0 to 7 is acidic, a pH of 7 is neutral, and a pH of 7 to 14 is basic

pH Value of &

Substance that is neutral, it's not an acid or base

0-6 Acid

Having a pH less than 7

8-14 Base (Alkaline)

Having a pH greater than 7

combustible

capable of catching fire or burning

malleable

easy to shape or bend

ductile

A term used to describe a material that can be pulled out into a long wire.

Oxidation

A chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust

Law of Conservation

matter cannot be created or destroyed, it is all still present.

balanced equation

a chemical equation in which mass is conserved; each side of the equation has the same number of atoms of each element

precipitate

A solid that forms from a solution during a chemical reaction.

oxygen, carbon, hydrogen, and nitrogen

What 4 elements make up 90% of an organisms mass?

Isotope

What is it called when an element has a different number of neutrons than normal?