Physics

Gas Laws Standard Temperature and Pressure (STP) Standard temperature: 0?C or 273 K Standard pressure:1 atm, 760 mm Hg, or 101.3 kPa Boyle?s Law The pressure of a dry gas is inversely proportional to its volume if the temperature is held constant. Inverse Proportion two terms related so that, if one term increases, the other term decreases Boyle?s Law P V , PV = k P1V1 = P2V2 As pressure increases, volume decreases. 6 Chemistry textbook, p. 250 7 Chemistry textbook, p. 250 P1V1 = P2V2 Sample Problem 1 A sample of gas occupies 352 mL at a pressure of 3.17 atm. If the P is reduced to 1.24 atm, what volume will result? (3.17 atm)(352 mL) = (1.24 atm)V2 900 mL = V2 A sample of gas occupies 200 mL at a P of 2.15 atm. If the P is reduced to 1.25 atm, what is V2? 344 mL 537 mL 98 mL 89 mL

Periodic Trends 1 Sizes of Atoms Increase from top to bottom on the periodic table Why? There are higher energy levels, and electrons are farther from the nucleus. Atomic Radii Sizes of Atoms Decrease from left to right on the periodic table Why? There are more protons in the nucleus attracting more electrons (electrostatic attraction). Atomic Radii Atomic Radii 4 p. 113 of Chemistry textbook (BJU Press) Question Why do atoms get larger as you go down the periodic table? They are heavier. They are less dense. Electrons are further from the nucleus. Electrons are bigger. 5 (Comparing the size of an atom to that of its ion, not going across or up the table) Sizes of Atoms Ionic Radii Sizes of Atoms Atoms that lose outer electrons have smaller positive ions (metals).

The Electron Structure of the Atom The quantum model emphasizes the wave nature of electrons. The Quantum Model Quantum numbers are solutions to the wave equations of electrons. Scientists use a set of 4 quantum numbers to determine an electron?s location around an atom. Quantum Numbers Electrons exist in principal energy levels that correspond to Bohr?s orbits: 1, 2, 3, 4, 5, ? Principal energy levels are divided into 4 types of sublevels: s, p, d, and f. Where are the Electrons? The sublevels contain orbitals. Each orbital can hold up to two electrons. Where are the Electrons? Identifies the principal energy level Correlates to Bohr?s orbits n = 1, 2, 3, 4, 5, 6, or 7 for the ground state e?. The total number of e? in a level is 2n2. Principal Quantum Number (n) Level Total # e? 1

Section 2C States of Matter Kinetic-Molecular Theory All particles are in motion. Add energy = increase motion. Motion tries to tear apart matter. Attractive forces hold matter together. Attractive ? electrical, between particles Disruptive ? caused by kinetic energy (motion) Balance between these forces determines state. Kinetic-Molecular Theory Two Forces Solid Low energy Touching Locked in place Only vibrate (The inter-molecular forces are higher in energy than the kinetic energy.) 4 p. 41 of Chem. textbook Liquid More kinetic energy Still touching Not locked in place Can roll around (The intermolecular forces are almost equal to the kinetic energy.) 5 p. 41 of Chem. textbook Atoms are touching. Attractions are greater than repulsions. Atoms roll around. Atoms are small.

The Classification of Matter Matter Matter is described as ?anything that takes up space and has mass.? Matter Matter was created ex nihilo, which means ?from nothing.? Science Guess Scientific method Faith Observation Question How can we know where matter comes from? 4 Atom - Clipart.com Item #20307567 Organization of Matter Pure substances Mixtures Is a substancepure or a mixture? Determined by: Physical properties Chemical properties Physical Properties Physical properties can be measured without changing the material into another substance. They describe how a substance is by itself. The following terms are examples of physical properties: density density describes how the particles are packed into a material malleability malleability