Chemistry is the study of the composition, structure, and properties of matter and the changes it undergoes.

Physical Properties-can be observed & measured w/o changing the chemical makeup of the substance Physical Properties of Water Water’s freezing point is 0 o C Water is a universal solvent (Most substances dissolve in it).Water-based solutions are called aqueous solutions. Water is clear, colorless, odorless, & tasteless Density-is a measure of the mass of a material in a given volume. Water’s density is 1.00 g/mL

Density Calculations Formula Multiply both sides by v To solve for mass The "v's" cancel out Mass formula m = v x D To solve for volume Divide both sides by density The “D’s” cancel out Volume formula

Practice Problems-Density A sample of aluminum metal has a mass of 8.4g.The volume of the sample is 3.2cm 3.Calculate the density. What is the volume of a sample of liquid mercury that has a mass of 76.2g, given the density of mercury is 13.6 g/mL? What is the mass of a sample of material that has a volume of 55.1cm 3 and a density of 6.72 g/cm 3 ?

Pure substance-have uniform and definite composition can’t be broken down. Element – a fundamental form of matter with the same chemical and physical properties that can’t be broken down into any more unique parts by ordinary chemical or physical means Atom – the smallest particles of matter that retainsall of the properties of an element Example Let’s say that I had a brick of pure gold. This would be an element, because no matter how many times I broke it’s many atoms apart, every atom would still be gold.

Elements one of the 100+ pure substances that makes up everything in the universe

Examples of Elements H= Hydrogen C= Carbon O= Oxygen N= Nitrogen S= Sulfur Na= Sodium Ca= Calcium K= Potassium I= Iodine Cl= Chlorine P= Phosphorus

Molecules– are made of 2 or more different atoms combined by chemical bonding (glue that holds elements together to form compounds) Compounds - 2 or more elements chemically combined to form a new substance with new properties Molecules & Compounds

Two identical elements combine to form a molecule This happens with the following elements: 1)H 2 2)N 2 3)O 2 4)F 2 5)Cl 2 6)Br 2 “GEN-U-INE DIATOMICS” CAN SERVE AS A GOOD MEMORY DEVICE FOR ALL COMMON DIATOMIC ELEMENTS. THE NAMES OF THE DIATOMIC ELEMENTS END IN EITHER GEN OR INE, AND U BETTER REMEMBER THEM. DIATOMIC MOLECULES

Two Types of Mixtures Homogenous Mixtures – Do Not have visibly different parts Colloid-mixture containing solid particles that are small enough to remain suspended Example-Milk Solutions-homogenous mixture of two or more substances Solute-dissolved substance in a solution, usually the component present in the smaller quantity Example: salt in water Solvent-dissolving agent in a solution, usually the component present in the larger quantity Example: Water Examples: Seawater A mixture is a blend of two or more pure substances. It can be broken down into two or more pure substances

Heterogeneous Mixtures: – Has visibly different parts Suspension-mixture containing large, dispersed solid particles that can settle out or be separated by filtration Examples: Chocolate Chip Cookies, Foul Water Sample

Chemical symbols are the letters in the language of chemistry that represent elements and formulas that describe atoms, elements & compounds. Chemical formula are the words in the language of chemistry that represents a different chemical substance. Chemical equation are the sentences in the language of chemistry that summarize the details of a particular chemical reaction. Chemical reactions are the breaking and forming of chemical bonds, causing atoms to become rearranged into new substances.

reactants products Chemical equations show the conversion of reactants (the molecules shown on the left of the arrow) into products (the molecules shown on the right of the arrow). A + sign separates molecules on the same side The arrow is read as “yields” Example C + O 2  CO 2 This reads “carbon plus oxygen reacts to yield carbon dioxide” Parts of a Chemical Equation

4 Al () + 3 O 2 (g) ---> 2 Al 2 O 3 (s) 4 Al (s) + 3 O 2 (g) ---> 2 Al 2 O 3 (s) Reactants-the original (starting) substances Products-new substances formed from the rearrangement of the reactant atoms The numbers in the front tell you how many molecules are represented they are called coefficients. The subscripts tells you how many atoms of a particular element are in a compound. Chemical Equation

 Solid (s)  Gas (g)  Liquid (l)   Aqueous solution (aq)  Catalyst H 2 SO 4  Escaping gas (  )  Change of temperature (  ) Symbols Used in Chemical Equations

Particulate Level Diagrams

CHEMICAL REACTIONS Reactants: Zn + I 2 Product: Zn I 2

The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction, C + O 2  CO 2, contains the same information as the English sentence but has quantitative meaning as well. CHEMICAL REACTIONS

Protons p + - positive charge, in nucleus Electrons - e - negative charge, orbiting nucleus Neutrons n 0 – no charge, in nucleus ++ + Like charges repel Unlike charges attract