CHEM 1211K 1st Edition Exam 1 Study Guide Lectures 1 9 Chapter 1 Matter Measurement and Problem Solving Practice Questions 1 A chemist mixes sodium with water and witnesses a violent reaction between the metal and water This is best classified as a an observation b a law c a hypothesis d a theory 2 Which change is a physical change a wood burning b iron rusting c dynamite exploding d gasoline evaporating 3 Perform the calculation to the correct number of significant figures 8 01 7 50 3 002 a 0 1698867 b 0 170 c 0 17 d 0 1700 4 Which property of rubbing alcohol is a chemical property a it s density b it s flammability c it s boiling point d it s melting point 5 Convert 85 0 degrees F to K a 181 1 K b 358 K c 29 4 K d 302 6 K Concepts All matter is composed of atoms and molecules Laws hypotheses and theories all give rise to predictions that can be tested by experiments carefully controlled procedures designed to produce critical new observations A pure substance can either be an element which cannot be chemically broken down into simpler substances or a compound which is composed of two or more elements in fixed proportions We can classify the properties of matter into two types physical and chemical In chemical and physical changes matter often exchanges energy with its surroundings Derived units are those formed from a combination of other units Key Equations K C 273 15 C F 32 1 8 D M V Chapter 2 Atoms and Elements Practice Questions 1 Two samples of a compound containing elements A and B were decomposed The first sample produced 15g of A and 35g of B The second sample produced 25g of A and what mass of B a 11g b 58g c 21g d 45g 2 Which idea came out of Rutherford s gold foil experiment a Atoms contain protons and neutrons b Matter is composed of atoms c Elements have isotopes d Atoms are mostly empty space 3 Determine the number of protons and neutrons in the isotope Fe 58 a 26 protons and 58 neutrons b 32 protons and 26 neutrons c 26 protons and 32 neutrons d 58 protons and 58 neutrons 4 Which pair of elements do you expect to be most similar in their chemical properties a K and Fe b O and Si c Ne and N d Br and I 5 A 20 0g sample of an element contains 4 95x10 23 atoms Identify the element a Cr b O c Mg d Fe Concepts Each element is composed of indestructible particles called atoms All atoms of a given element have the same mass and other properties Atoms of one element cannot change into atoms of another element In a chemical reaction atoms change the way they are bound Robert Millikan measured the charge of the electron which led to the calculation of the mass of an electron Nuclear theory states that the atom is mainly empty space with most of its mass concentrated in a tiny region called the nucleus Atoms are composed of three fundamental particles the proton the neutron and the electron The periodic table tabulates all known elements in order of increasing atomic number The atomic mass of an element listed directly below its symbol in the periodic table Key Equations Mass number Protons Neutrons Atomic Mass Fraction of isotope x mass of isotope 1mol 6 0221421 x 10 23 particles Chapter 3 Molecules Compounds and Chemical Equations Practice Questions 1 Which substance is an ionic compound subscript a SrI2 b N2O4 c He d CCl4 2 What is the correct formula for the compound formed between calcium and sulfur subscript a CaS b Ca2S c CaS2 d CaS3 3 What is the formula for manganese IV oxide subscript a Mn4O b MnO4 c Mn2O d MnO2 4 Name the compound HNO2 aq subscript a hydrogen nitrogen dioxide b hydrogen nitrate c nitric acid d nitrous acid 5 Determine the mass of potassium in 35 5g of KBr a 17 4g b 0 298g c 11 7g d 32 9g Concepts Chemical bonds the forces that hold atoms together in compounds arise from the interactions between nuclei and electrons in atoms In an ionic bond one or more electrons are transferred from one atom to another In a covalent bond one or more electrons are shared between two atoms A compound is represented with a chemical formula which indicates the elements present and the number of atoms each An empirical formula gives only relative number of atoms Elements can also be divided into two types molecular elements and atomic elements The formula mass of a compound is the sum of the atomic masses of all the atoms in the chemical formula The mass percent composition of a compound indicates each elements percentage of the total compounds mass Chemical equations are balanced when the number of each type of atom on the left side is equal to the number on the right Common functionalized hydrocarbons include alcohols ethers aldehydes ketones carboxylic acids esters and amines Key Equations Mass of element X mass of X in 1 mol compound mass of 1 mol compound x 100 Molecular formula n X empirical formula n molar mass empirical formula molar mass