Chemistry 111 Chapter 11.1 What is chemistry- Chemistry: the study of matter, its transformations and how it behaves.1.2 Classification of Matter- Properties: properties that matter can be described by (composition)- Element: simplest type of matter, cannot be broken down or separated into simpler substanceso 118 elements (90 exist in nature)- Atom: smallest individual unit of an element.- Pure substance: contains only one type of element or compound and has one fixed chemical composition.- Physical properties: properties of a chemical substance are those that do not change into the chemical composition of the material when they are measured.(physical state, color, density)- States of matter: Three physical states are solid, liquid and gas.o Solid-Dense material with a defined shape, molecules are packed together, molecules vibrate but do not move past each other.o Liquid: Dense but flows and takes shape of container, molecules are closetogether, molecules move past each other.o Gas: no fixed shape or volume, molecules move rapidly and are spaced widely apart. - Melting point: the temperature at which a slid is converted into a liquid- Chemical properties: properties that involve a chemical change in the material and often involve a substance interacting chemicals.1.2 Classifying Mixtures- Mixture: a substance that is made up of 2 or more elements or compounds that have not reacted chemically.- Homogenous mixture: mixtures that have a constant composition throughout the material (in solution)- Heterozygous mixture: a mixture in which the composition is not uniformo Both mixtures can be separated into individual components Measurements- Temperature- T(°C ¿=T(° K)−273.15-180 ℉=1℃-95℉=1 ℃- DensityoDensity=Mass/VolumeSignificant Figures- 1. All non-zero digits and zeros between non-zeros are significant- 2. In numbers containing a decimal pointo all zeros at the end of the number are significanto all zeros at the beginning of the number are not significant- 3. In a number with no decimal points, all zeros at the end of the number are notsignificanto x or / :answer has the same significant figures as number with fewest significant figures.o + or - :answer has the same number of decimal places as number with the fewest decimal places. 1.3 Precision and Accuracy- Precision: How close the values is in a set of measurements are to one another- Accuracy: How close a measurement or set of measurements is to a real value.Components of an atom- Atoms consist of 3 subatomic particles: protons, neutrons and electrons o Protons: +1 and have a mass of 1o Neutrons: no charge and have a mass of 1o Electrons -1 and have a mass <1- Atomic nucleus: small region of high density at center of the atom, made up of protons and neutrons.- Ion: an atom with an unequal number of protons and electrons- Cation: when an ion has more protons than electrons, overall positive charge- Anion: has more electrons than protons, overall negative charge.2.1 Atomic number- Isotopes: atoms that have same atomic number but different mass numberso Names by using element name and mass number- Atomic Weight: the average mass of all naturally occurring isotopes of that element, taking into account the relative abundance of the isotopes.- Percent abundance: The percentage of the atoms of a natural sample of the pure element is represented by a particular isotope.o Calculate the atomic weight2.2 Periodic Table- Groups: elements in vertical columnso Elements in the same groups have same chemical and physical properties.- Periods: elements in horizontal rows- Alkali metals: groups 1A, shiny solids that react with air, water and halogens- Halogens: group 7A- Alkaline earth metals: most of group 2A, react with water to from alkaline solutions- Chalcogens: Group 6A.- Main group elements: the elements in group A, representative elements - Transition metals: elements in group B- The elements on the left side are metals, right side are nonmetals, and elements at the interface of these two regions are metalloids and semimetals- Allotropes: form from same elements, but different chemical and physical properties2.3 Covalent Compounds- Covalent compounds: consist of atoms of different elements held together by covalent bonds.o Molecular covalent compound: made up of individual molecules. Ie. Water (H2O oxygen and hydrogen held together by covalent bonds)o Network covalent compound: whole molecules are held together by covalent bonds forming one big molecule. - Molecular formula: contains a symbol for each element present and a subscript number to identify the number of atoms of each element in the molecule. The simplest way to represent a molecule. - Empirical formula: represents the simplest whole-number ratio of elements in a compound. - Structural formula: shows the linkage of all the atoms in the molecule.- Condensed structural formula: lists the atoms present in groups to indicate connectivity between the atoms.- Wedge-and-dash model: two-dimensional representation of a three-dimensionalstructure that can easily be drawn on paper - Ball and stick model: shows atoms as colored spheres connected by sticks that represent covalent bonds.- Space-filling model: interpenetrating spheres represent the relative amount of space occupied by each atom in the