Chemistry+Review

Chemistry
= Matter = Well first of all, //matter is anything that has mass and takes up space//. It is the "stuff" that everyone talks about. There is a lot of information that deals with matter. **ALL matter has chemical and physical properties and every physical and chemical change includes a change in energy.** Matter always has mass. //Mass is the measurement of the amount of matter (stuff) in an object.// Mass is different from weight. //Weight is the measure of the force of gravity.// **While weight changes mass stays the same.** Matter also deals with chemistry. //Chemistry is the study of properties and changes of any type of matter.// Matter helps form substances too. //Substances are a single kind of matter that is pure.// Matter can be measured, but in a different way. Scientists use the International System of Units to measure matter. When matter changes it uses energy. //Energy is the ability to do work or to cause change.// There are a couple changes, but two are Exothermic Change and Endothermic Change. //Exothermic Change a change in which energy is released//. An //Endothermic Change a change in which energy is taken in.// Just remember it by __ex__othermic means release and __ex__haling mean release air. = = = = = Elements/Periodic Table = Elements are the fun part of chemistry. There are 118 elements in the periodic table. 90 of them are found in nature. The other ones are man made. Dmitri Mendeleev, a Russian scientist, discovered the patterns of the elements. Elements can be identified by the number of protons in its nucleus. The periodic table is set up into rows and columns. The vertical column is referred to as a Group or Family. A horizontal row is considered a period. is a The family has similar characteristics. There are different families. There is the Carbon Family which share their electrons most of the time. Halogens have tendencies to form singly-charged negative ion. The Nitrogen Family elements all have 5 electrons on their outermost shell. Noble Gases have very weak inter-atomic forces of attractions. They have very low melting and boiling points. Oxygen Family consist of chalocogenides which are mainly sulfides selenides and tellurides. These are common in the form of minerals. With one element there is a lot of information. There is its atomic mass, atomic number and its symbol. An element's //atomic mass is the number of protons that are in the nucleus.// The //atomic number is is the number of protons that are in the nucleus.// Every element consists of atoms. //Atoms are the basic unit of an element//. There are three different kinds of atoms. There are protons, electrons and neutrons. //Protons are atoms that have a positive charge. Electrons are atoms that have a negative charge and neutrons are atoms that have no charge or are neutral.// Scientists John Dalton concluded that all elements are made of atoms. Even though elements help create our world, they do end up with some flaws. Some would be ions and isotopes. //Ions are an atom or group of atoms that has a positive or negative electric charge; forms by atoms gaining or losing electrons. Isotopes are an atom of one element that has a different number of neutrons than another atom of the same element.// Even though these aren't bad, they're not perfect.

= = = = = = = = = = = Changes of Matter, Compounds and Mixtures = Two other changes in matter are physical and chemical changes. A //physical change is a change in a substance that does not change its identity.// Some examples would be boiling water, ice and something changing colors.//A chemical change is a change in which one or more substances combine or break apart to form new substances.// Some examples would be rusting, baking and wood burning. There are two kinds of mixtures. They are Heterogeneous Mixtures and Homogeneous Mixtures. A //heterogeneous mixtures is a mixture in which pure substances are unevenly distributed throughout the mixtures.// Some examples are salads, smoothie and M&M's. Another mixtures is a homogeneous which is a mixture in which pure substances are evenly distributed throughout the mixtures. Examples are Kool-Aid and Hawaiian Punch. Elements help make compounds. //Compounds are a pure substance made of two or more elements chemically combined in a set ratio.// Examples would be table sugar, water and salt. There are many different changes in state. Mainly with water. It's melting, freezing, evaporation and vaporization. // Evaportation is vaporization that takes place only on the surface of a liquid.(Ex. When a drink gets water on the sides of a glass.) Vaporization is the change in state from a liquid to a gas. (Ex. boiling water). Boiling point is the temperature at which a liquid boils. Condensation is the change in state form a gas to a liquid. Ex. clouds. Sublimation is the change from a solid to a gas. Ex. Dry ice .//

=Balancing Chemical Equations= Great practice here. @http://www.sciencegeek.net/Chemistry/taters/EquationBalancing.htm http://education.jlab.org/elementbalancing/index.html