CHEM 130 Exam 1Questions With Accurate Answers 100% Verified

Chemistry - correct answers Study of matter and the changes that matter undegoes Matter - correct answers Anything that has mass and occupies space Steps of the Scientific method - correct answers 1) Observation 2) Hypothesis 3) Experiment 4) Model (theory) 5) Further experiment or alter model Quantitative properties - correct answers Properties that can be measured (time, temperature, mass, distance) Lowest possible temperature on Kelvin scale - correct answers 0 Exact number - correct answers 1) Defined value 2) Determined by counting Inexact number - correct answers Measured by any method other than counting (length, mass, volume, time, speed) Significant figures in addition and subtraction rule - correct answers The answer cannot have more digits to the right of the DECIMAL POINT than any of the original numbers Significant figures in multiplication and division rule - correct answers The answer cannot have more SIGNIFICANT FIGURES than the original number with the smallest NUMBER of significant figures Subtance - correct answers A form of matter that has definite composition and distinct properties (Salt, iron, water, carbon dioxide) - an element or a compound Solid - correct answers Particles are held close together in an orderly fashion with little freedom of motion - Does not conform to the shape of its container Liquid - correct answers Particles are close together but are not held rigidly in position; they are free to move around - Conforms to the shape of the part of the container it fills Gas - correct answers Particles are separated by distances that are very large - Assumes both shape and volume of the container Mixture - correct answers A physical combination of two or more substances Homogeneous mixture - correct answers Uniform throughout (aka solution) - every portion of the mixture is like every other portion - Apple juice, sea water Heterogeneous mixture - correct answers Composition is not uniform - Composition varies from where you sample it - Mixing Extensive property - correct answers Depends on the amount of matter Cannot be used to help identify a substance because it changes - Mass and volume - Values of the same extensive property can be added together Intensive property - correct answers Does not depend on the amount of matter Can be used to help identify a substance because it does not change with amount of matter present - Boiling point, density, freezing point, color Physical PROPERTY - correct answers Can be observed and measured without changing the identity of a substance - Color, melting point, boiling point Physical changes - correct answers A change of matter from one form to another without a change in chemical properties Chemical PROPERTY - correct answers Any property of a substance that cannot be studied without converting the substance into some other substance - becomes evident during a chemical reaction - Iron, flammable, reactive Chemical CHANGE - correct answers A process in which one or more substances are changed into one or more new substances - Corrosion or oxidation - After a chemical change, the original substance no longer exists Atom - correct answers Smallest quantity of matter that still retains the properties of matter Element - correct answers Substance that cannot be broken down into two or more simpler substances Radiation - correct answers Emission and transmission of energy in the form of waves Alpha rays - correct answers Protons (positive charge) 2 protons, 2 neutrons Beta rays - correct answers Electrons (negative charge) Gamma rays - correct answers No charge, no mass - form of light with the highest energy Protons - correct answers Positively charged particles found in the nucleus Neutrons - correct answers Neutral particles found in the nucleus - Slightly larger than protons Electrons - correct answers Negatively charged particles distributed around the nucleus Nucleus - correct answers Heavy, dense center Atomic number and mass number - correct answers A: Mass number (sum of protons and neutrons) Z: Atomic number (number of protons) Isotopes - correct answers Atoms of the same element that have the same number of protons but different numbers of neutrons - Top number different, bottom number same Groups - correct answers Vertical columns of the periodic table - Elements in the same group tend to show similar chemical properties Periods (rows) - correct answers Horizontal rows, in order of increasing atomic number Metals - correct answers Good conductors of heat and electricity (left side) Nonmetals - correct answers Poor conductors of heat or electricity (right side) - noble gases Metalloids - correct answers Intermediate properties - stair steps alkali metals - correct answers group 1A elements alkaline earth metals - correct answers group 2A Halogen - correct answers Group 7A Noble gas - correct answers Group 8A Average atomic mass - correct answers The weighted average mass of all the naturally occurring isotopes - Isotopic mass (amu) x natural abundance (%) Mole - correct answers The amount of a substance that contains as many elementary entities as there are atoms in exactly 12 g of Carbon-12 - 1 mole = 6.022x10^23 items (atoms, molecules, ions)