An object has a mass of 12.1 kilograms and a density of 4.5 g/ml. What is the volume of this object in fluid ounces? (1 fl oz = 29.

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1 Week 4 Wednesday, February 01, 2012 Due next week: Lecture Quiz 1 Located in D2L lecture course 8 questions (calculations from ch 2) Best of 3 attempts (120 min/attempt) Calculation questions are graded all-or-nothing (except 0.5 pt for the unit) Expected to be individual(your own work) Chapter 5 reading Week 4 MasteringChemistry Exp 6 Prelab Video/Quiz Continue memorizing list of common element names and symbols for Exam 1 Tonight (6:00-7:15 pm): Questions Warm-up: conversion practice Skipping over: matter, changes, properties, and law of conservation of mass Discussion: temperature conversions Skipping over: history (Dalton, Thomson, Rutherford) Lecture: the atom, atomic number, periodic table Discussion: ions, isotopes, mass number Conversion practice An object has a mass of 12.1 kilograms and a density of 4.5 g/ml. What is the volume of this object in fluid ounces? (1 fl oz = ml) A sample of a liquid weighs 42.5 lb and has a density of 0.95 g/cm 3. What is its volume in gallons? 90-week4 Page 1 90-week4 Page 2

2 Chapter 3: Matter and Energy Elements, compounds, and mixtures Matter has both mass and volume. Elements have only one type of: Compounds: pure substances with more than one different element Chemical formulas: show ratio of elements in a pure substance NaCl: H 2 O 2 : Fe: Br 2 : Homogeneous mixtures: Pure substances: Mixtures: Heterogeneous mixtures: 90-week4 Page 3 90-week4 Page 4

3 Physical and chemical changes Chemical changes Physical changes: change the form or appearance of substance, but still have Phase changes are physical changes (between solid, liquid, and gas) Liquid water Chemical change: A new type of matter is formed A new chemical formula is written Also known as a chemical reaction Cluesthat a chemical change has occurred (all of these are evidence that a new substance has formed) Color change Odor, gas evolved (but not just from boiling) Flame, burning Temperature change on its own Solid ice Gas: water vapor, steam Chemical equation represents a chemical reaction: Dissolving, mixing, grinding are physical changes Filtration, distillation, and other methods of separating mixtures into their pure substances are also physical changes. Reactant(s) chemical reaction Product(s) 90-week4 Page 5 90-week4 Page 6

4 Physical and chemical properties Law of conservation of mass Physical propertiesdescribe the physical form of a substance. They can involve physical changes Boiling point, freezing point, melting point Color, odor, taste, consistency Density Law of conservation of mass: in a chemical reaction, matter can be neither... Chemical propertiesdescribe behavior of a substance in chemical changes (usually in presence of other chemicals or heat) Sodium fizzes and ignites in water Magnesium does not react with water Identify the type of property: Baking soda will react with vinegar but not with water Baking soda is a fine, white powder Hydrogen is explosive 90-week4 Page 7 90-week4 Page 8

5 Temperature Fahrenheit/Celsius conversions Temperature: measure of atomic or molecular motion measured with... F = 1.8( C) + 32 C = ( F -32) 1.8 K C F Kelvin (SI unit) degree Celsius degree Fahrenheit C F 85 F =? C C 32 F 85 F =? K C 212 F K = C or C = K C =? K 90-week4 Page 9 90-week4 Page 10

6 Chapter 4: Atoms and elements Electrons Laws: constant composition and conservation of matter (1700s) Dalton's atomic theory: (early 1800s) Matter is made of indestructible atoms Atoms of one element are the same Atoms combine in simple ratios to make compounds Discovery of the electron:(j. J. Thomson, late 1800s) Cathode ray tube (beam of electrons) Electrons are: the same no matter which substance they come from. particles that are smaller than atoms. negatively charged. Plum pudding model 90-week4 Page week4 Page 12

7 Discovery of the nucleus Modern nuclear model of the atom Rutherford's gold foil experiment (1909): to test plum pudding model Conclusions: Atoms are mostly empty space Atoms must contain a dense positively-charged core that is small but massive Nucleus: Rutherford's name for the (+)-charged core of the atom Modern model of the atom: Expected: alpha particles to fly straight through foil Actually: most went straight through, but some were strongly deflected. 3 subatomic particles: + protons p + neutrons n 0 - electrons e - 90-week4 Page week4 Page 14

8 Elements Periodic table The number of protonsdetermines which element an atom is. Atomic number (AN) = # p + in nucleus 1 H XXXX 6 C XXXX AN is found on the periodic table! Dimitri Mendeleev discovered that elements with similar properties are found every 8 elements when put in order of atomic number. He, Ne, and Ar are all unreactive gases (atomic numbers 2, 10, and 18) Hydrogen has protons in its nucleus. Carbon has protons in its nucleus. Periodic table: Columns = groups or families (18 groups) Rows = periods (7) 90-week4 Page week4 Page 16

9 Sections of periodic table Main group Transition elements Inner transition elements Metals: Nonmetals: Metalloids: 90-week4 Page 17