UT Online High School Chemistry A Final Exam Thorough Review, Complete Solution

UT Online High School Chemistry A Final Exam Thorough Review, Complete Solution Accuracy how close a measurement is to the true value dependent variable changes in response to the independent variable (what you measure in an experiment and what's affected during the experiment) Hypothesis a proposed explanation for an observation Independent variable (often denoted by x) doesn't depend on something else Scientific notation how scientists handle large or small numbers Significant Figure all the nonzero digits of a number and the zeros that are included between them or that are final zeros and signify accuracy SL unit for mass based on meter, kilogram, second, ampere, kelvin, and mole w/ set of prefixes to indicate multiplication or division by a power of ten Theory well-supported explanation that's been repeatedly tested Aristotle laid the foundation for science (constructed an explanation for his observations of falling objects)(only made logical assumptions from observations) Galileo tested his theories (T/F) Science cannot prove anything 100% (true) science cannot prove anything 100% Science Process that follows rules/procedures to answer questions about the natural world How many new experiments does it take to disprove a theory? It takes one new experiment to disprove a theory The scientific method is an ___ process The scientific method is an ONGOING (or fluid) process Scientific Method Steps Observe, hypothesis, test hypothesis, make conclusion, report result precision How close two measurements are to each other Write 7.7847 * 10^4 in standard notation w/ 2 sig figs 78,000 Write 7.4 * 10^-2 in standard notation w/ 2 sig figs 0.074 Physical properties associated w/ characteristics of molecules that can be tested w/out changing the chemical make-up of compounds (magnetism, boiling point, melting point, color, taste) (T/F) Decomposition is considered a physical change False, decomposition is a chemical change because molecules are changing Chemical change Chemical reaction, chemical makeup is changed Physical change When a substance's physical form is changed What is the difference between a property of matter and a change in matter? Properties tell us about elements, and changes determine these properties (physical/chemical) Cutting paper Physical (physical/chemical) boiling vinegar Physical (physical/chemical) Iron nail rusting Chemical (physical/chemical) Reacting magnesium with hydrochloric acid Chemical Four states of matter Solid (snow), liquid (water), gas (helium), plasma (lightning strikes) 3 Criteria of classifying matter Compressibility, shape, volume Shape and volume are defined in terms of ___ or ___ Definite (can't be changed) or Indefinite (can be changed) (T/F) Liquids are compressible False, liquids are not compressible (T/F) Gases have higher compressibility than liquids True, gases have higher compressibility than liquids What state of matter has an indefinite shape and is compressible? Liquids Which state of matter is compressible and has indefinite shape? Gases (T/F) Liquids have indefinite shapes, but are still incompressible True, liquids have indefinite shapes but are incompressible Solids have ___ volume definite Solids have a ___ volume, ___ shape, and are ___. Solids have a DEFINITE volume, DEFINITE shape, and are INCOMPRESSIBLE extensive property depends on the amount of matter in a sample (ex? mass and volume) intensive property does not depend on the amount of matter in a sample (ex? boiling point, freezing point, temp, color, hardness, density of water. 1 cup has the same density of 1 gallon) (intensive/extensive) Melting Point Intensive (intensive/extensive) Length Extensive (intensive/extensive) width Extensive (intensive/extensive) Malleability Intensive (intensive/extensive) Weight Extensive (intensive/extensive) Luster Intensive (intensive/extensive) Mass Extensive (intensive/extensive) 12.6 grams Extensive (intensive/extensive) 2.30 liters of gas Extensive Pure substance constant composition Mixture a combination of substances in which individual substances retain their own properties Compounds pure substances that can be broken down by chemical changes are called compounds Elements pure substances that can't be broken down into simpler substances by chemical changes Mixtures composed of molecules that include multiple separate compounds (heterogenous or homogenous mixture) Heterogenous mixture unevenly mixed (italian dressing) Homogenous mixture a mixture that is the same throughout (maple syrup) (heterogenous/homogenous) Brass, which is made up of copper and zinc Homogenous (heterogenous/homogenous) Muddy water Heterogenous (heterogenous/homogenous/element/compound) copper wire Element (heterogenous/homogenous/element/compound) Pure H2O Compound Compounds can be separated using ___ changes Compounds can be separated using CHEMICAL changes Atoms are made up of electrons, protons, neutrons Structure of the atom was developed since ___ BC 400 BC Electromagnetic spectrum the range of electromagnetic waves Electron negative subatomic particle Excited state When electron has more energy that usual Frequency Number of oscillations of a wave per second Ground state The lowest energy state of an atom Isotope An atom with the same number of protons and a different number of neutrons from other atoms of the same element. Mass Number protons + neutrons Orbital Where electrons are Mass of proton or neutron 1.67*10^-27 kg Mass of electron 9.1 * 10^-31 kg Atomic number Number of protons We were not able to see atoms until the ___'s using microscopes 1930's The atom first came about from a greek philosopher named___. Democritus J.J. Thomson (1897) Cathode ray experiment (discovered electron) Ernest Rutherford (1911) Gold Foil Experiment Discovered the nucleus dense, positive charge in the center of the atom Nuclear Model A single electron is __% the mass of a single proton or neutron 0.05% If two different atoms of the same element do not have the same mass, what is causing the difference in their masses? Different number of neutrons How many protons and neutrons would Al-27 have? 13 protons and 14 neutrons (27-13=14) Write the isotope notation that would have 8 protons and 10 neutrons. Oxygen-18 Steps to calculate average atomic mass Turn all of your percents into decimals by dividing by 100, multiply the decimal for each isotope by the mass number, add up the numbers for the average atomic mass An element has three isotopes X-4.00 = 87.46% X-5.00 = 11.57%