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Think of the word “elementary”?

ATOMS ELEMENTS COMPOUNDS or make up

ATOMS ELEMENTS COMPOUNDS -smallest building block -make up all matter make up ELEMENTS COMPOUNDS -an atom or collection of atoms that are the same -may be chemically linked -1 particle made of 2 or more atoms -chemically linked in a fixed proportion or

Water → Hydrogen + Oxygen Compounds can be broken down into simpler substances through a chemical change, but elements cannot. Note: properties of compounds are very different from the elements that compose them! heat Sugar → Carbon + Water electricity Water → Hydrogen + Oxygen Chemical change – produces matter with a different composition than the original matter.

Matter Substance Element Compound Mixture Homogenous Heterogeneous

Is it a substance or a mixture? If the composition is fixed – it is a substance If it varies – it is a mixture Example: There are multiple types of milk, blends of gas, different recipes for pizza – these are mixtures. Carbon dioxide is always carbon dioxide – it is a substance.

Chemical Symbols Symbol system began thousands of years ago with the alchemists. Today’s symbols were developed by Jons Jacob Berzelius (1779-1848). Each element is represented by one- or two- letters. (Ex: Hydrogen, H and Iron, Fe)

Chemical Formulas Abbreviated using chemical symbols Subscript numbers show how many atoms of each element make up the compound. Example: H2O has 2 hydrogen atoms and 1 oxygen atom in every molecule. Na3PO4 (sodium phosphate) has 3 sodium atoms, 1 phosphorous and 4 oxygen atoms for every molecule.

Periodic Table Used to compare properties of elements. Elements are listed in order of atomic number, which is unique to each element. Elements are grouped into periods and groups. Periods – horizontal row. Within a period the properties of elements change. Groups – vertical columns. Within a group, elements share similar chemical and physical properties.

Chemical Changes – what chemistry is all about! Chemical properties – a substance’s ability to undergo a chemical change. Example: Iron’s ability to combine with oxygen to form rust (Fe2O3)

Chemical change = Chemical Reaction A new substance is always formed in a chemical reaction. Clues to if a chemical reaction has occurred: Transfer of energy (increase or loss of heat, light) Change in color Production of gas (bubbles) Formation of a precipitate – a solid that forms out of a liquid mixture. Manganese hydroxide precipitate

Reactants – substances orginially present Products – substances present after reaction CaO (s) + H2O (l) → Ca(OH)2 (aq) SO2 (g) + H2O (l) → H2SO3 (aq)

Law of conservation of mass In any physical or chemical change, mass is neither created or destroyed. The mass of the reactants will be equal to the mass of the products.

Compounds can be broken into simpler substances by chemical means Compounds can be broken into simpler substances by chemical means. Elements are the simplest unit of matter. Compounds can be broken down by heat and electricity. Carbon Calcium Potassium Iron

It is a chemical change. It produces heat and light and new substances (carbon dioxide, water, and ash) are formed. It has properties to oxygen because it is in the same group.