Transcript Chemistry
Chemistry Because it matters!! What is chemistry? Chemistry is the study of matter… Its structure, composition, properties, and the changes it undergoes. What is it made out of? How strong is this material? What happens when I try to burn this substance? What is matter? Matter is anything around us the has mass and volume. Mass =(amt of matter): balance - grams (g) Volume = (amt of space occupied): graduated cylinder- milliliters (mL) or metric ruler V = L x W x H – cubic centimeters (cm3) Making Observations Check out the various samples of matter…….. What are some things that you can observe about them? Are there any similarities or differences? Classifying Matter Matter can have different phases or physical states…. Solid Liquid Gas The 3 phases differ due to differences in the: 1) arrangement of their particles 2) attraction between their particles. http://www.youtube.com/watch?v=s-KvoVzukHo&feature=related Classification of Matter: Element Compound Mixture Matter Pure Substance (fixed composition) Elements Compounds Mixtures of Substances (composition varies) Heterogeneous Homogeneous Suspensions Solutions Elements vs. Compound There are about 115 different elements. Elements are pure substances composed of atoms that cannot be broken down any further. A particular element contains atoms having the same atomic number. Some examples: Iron (Fe) or Oxygen (O2) Compounds Compounds are pure substances composed of atoms from 2 or more different elements chemically combined in a fixed or definite ratio. The compound’s properties are not the same as its component’s original properties. Examples: Water (H2O) Sodium Chloride (NaCl) Chemical symbols Elements symbols Use one or two letters to represent name Always start with a capital letter If there is a second letter that it is lower case. Compounds Written with two or more capital letters in there symbol. Numbers written as subscripts show the number of elements H2O 2 hydrogen 1oxygen MgCl2 1 magnesium Models 1. Elements (made of a single kind of atom) Monatomic Element He 2. or Diatomic Element H2 Compounds (hook different atoms together to show they are chemically combined) Water is a compound (H2O) 3. Mixtures (the different substances aren’t hooked – shows they are physically combined) Mixture of Water (H2O) & Oxygen (O2) Vocabulary used to classify matter Substance- matter that you haven’t classified yet. Pure substance- same composition and properties though out a given sample Element- matter composed of identical atoms that cannot be further broken down by chemical means. Can be represented with a chemical symbol He of helium, C for carbon, or K for potassium. Compound- two or more different elements that at are chemically combined in a fixed ratio. A compound can be broke apart in chemical reaction. Ex H2O or C6H12O6 Vocabulary Cont. Mixture- are composed of two or more different substances that can be seperated by physical means. The proportions can be varied Each part of the mixture retains it own properties More on Mixtures Homogeneous looks same though out the sample. Evenly mixed, uniformly distributed Examples Air Kool-aid Apple juice Steel Heterogenous Visibly different parts which are not in the same amount through out the substance Examples Chex mix Granite Salad dressing Special mixtures Solution vs. Suspension Homogenous mixture Solute is dissolved in a solvent. Solute is the part being dissolved Solvent is the part doing the dissolving Heterogeneous Mixture Insoluble solid suspended in a liquid. Does not dissolve Will settle upon standing