Chemistry Final Exam Study Guide Chapters 1 3 Equations To Know o d m v o C F 32 F 5 C 9 F o F 9 F 5 C C 32 F o K C 273 15 o yield actual yield theoretical yield 100 Scientific Notation A systematic approach to research that begins with the gathering of information through observation and measurements Chemistry The study of matter and the changes it undergoes Qualitative Consisting of general observations about the system Quantitative Comprising numbers obtained by various measurements of the system Hypothesis Tentative explanation for a set of observations Compound Substance composed of atoms of two or more elements chemically united in fixed proportions Law A concise verbal or mathematical statement of a relationship between phenomena that is always the same under the same conditions Theory A unifying principle that explains a body of facts and or those laws that Substance A form of matter that has a definite constant composition and are based on them distinct properties o Water Ammonia Gold Oxygen their distinct identities o Air Milk Soft Drinks Cement Mixture Combination of two or more substances in which the substances retain o Mixtures can be separated into substances through physical methods Homogenous Mixture Where the composition of the mixture is the same throughout Heterogeneous Mixture Where the composition is not uniform Element A substance that cannot be separated into simpler substances by chemical means Compound A substance composed of atoms of two or more elements chemically united in fixed proportions o Compounds can be separated only by chemical means into their pure components Physical Property A property that can be measured and observed without changing the composition or identity of a substance Chemical Property A property where in order to observe it we must carry out a chemical change o Example Hydrogen gas burns in oxygen gas to form water Extensive Property A property where the measured value depends on how much matter is being considered Mass The quantity of matter in a given sample of a substance Weight The force that gravity exerts on an object Volume Length Cubed Intensive Property A measured value that does not depend on how much matter is being considered Density The mass of an object divided by its volume Macroscopic Properties Measurements that can be determined directly Microscopic Properties Measured values that must be determined by indirect methods on the atomic or molecular scale International System of Units SI Metric System Rules when Performing Arithmetic Operations in Scientific Notation Numbers need to be expressed with the same exponent o Addition or Subtraction N x 10m 10m Add or subtract N1 and N2 Exponents remain the same o Multiplication or Division N x 10m Numbers do NOT need to be expressed with the same exponent Multiply or divide N1 and N2 Add the exponents together if multiplying or subtract the exponents if dividing Rules for Determining Significant Figures Sig Figs o Any digit that is NOT zero is significant o Zeros between nonzero digits are significant o Zeroes to the left of the first nonzero digit are NOT significant o If the number is greater than 1 all zeros written to the right of the decimal point are significant If the number is less than 1 then only the zeros that are at the end of the number and any zeros between nonzero digits are o For numbers that do not contain a decimal point the trailing zeros may or significant may not be significant To avoid any confusion when not sure how to express an answer in decimal form express in Scientific Notation How to Handle Sig Figs in Calculations o For addition and subtraction the answer cannot have more digits to the right of the decimal point than either of the original numbers Error is in the last decimal place o For multiplication and division the number of sig figs in the final answer is determined by the original number with the LEAST number of sig figs o Exact numbers obtained from definitions or counting contain an infinite number of sig figs Chapter 2 Equations To Know o Mass Number of Protons Number of Neutrons o Neutron Mass Number Atomic Number Law of Definite Proportions Different samples of the same compound always contain its constituent elements in the same proportion by mass Law of Multiple Proportions If two elements can combine to form more than one compound the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers Law of Conservation of Mass Matter can neither be created nor destroyed Cation Ion with a positive charge o If a neutral atom loses one or more electrons it becomes a cation Anion Ion with a negative chage o If a neutral atom gains one or more electrons it becomes an anion Ionic Compound A compound formed from cations and anions Monatomic Ions Ions that contain only one atom o Na Cl Polyatomic Ions Ions containing more than one atom Molecule A combining of at least two atoms in a definite arrangement held together by chemical forces bonds Diatomic Molecule A molecule that contains only two atoms o OH CN o H2 Polyatomic Molecule Molecules containing more than two atoms Empirical Formula Tells us which elements are present and the simplest whole number ration of their atoms Acid A substance that yields hydrogen ions when dissolved in water o Oxoacids Acids that contain hydrogen oxygen and another element central element o Oxoanions Anions of oxoacids Naming Oxoacids and Oxoanions Top 10 List for Exam 1 o Matter is divided into two categories substances and mixtures They differ in the way in which they can be separated o We use a number of prefixes to represent really large or small numbers We can also represent these numbers using Scientific Notation o Sig Figs are the meaningful digit in a measurement or calculated quantity It is understood that the error is in the last digit o Dimensional Analysis is a method to convert between units by way of conversion factors These do not always contain an infinite number of sig figs It is important to make sure all units cancel leaving only the desired o There were a number of scientists who contributed to our understanding of Atomic Theory Not all of the significance of their work was understood at the time This one example demonstrates how the Scientific Method unit s works Dalton Atomic Theory States that all matter is composed of tiny indivisible particles called atoms that all atoms of the same element are identical that compounds contain atoms
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