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(BQ) Part 2 book “Nursing school extrance exam – Your guide to passing the test” has contents: Chemistry review, general science review, practice exam II, practice exam III. Invite you to consult the details.
CHAPTER 8 CHEMISTRY REVIEW CHAPTER SUMMARY This chapter is a general outline and review of the important chemistry concepts that are tested by many nursing school entrance exams Chemistry Review: Important Concepts I General Introduction A Description of How Nursing School Entrance Exams Test Chemistry This chapter reviews essential concepts in chemistry that are covered in many nursing school entrance exams Some tests contain specific chemistry or science sections; others ask you to be able to recognize important ideas and terms Some of these key concepts are atomic structure, the periodic table, chemical bonds, chemical equations, stoichiometry, energy and states of matter, reaction rates, equilibrium, acids, bases, oxidation-reduction, nuclear chemistry, and organic compounds B How to Use This Chapter This chapter is presented in outline format as a systematic presentation of important chemistry topics to help you review for your exam This does not constitute a comprehensive chemistry review—use it as an aid to help you recall concepts you have studied and to identify areas in which you need more study At the end of this chapter, you will find a list of references and resources for a more complete review Read each topic and answer the questions that follow After answering the sample test questions, you can pinpoint where you want to concentrate your efforts If a question poses particular difficulty for you, study more problems of this type The more you hone your problem-solving skills, understand basic principles, and recognize core terms, the more relaxed and confident you will feel on test day STUDY TIPS FOR CHEMISTRY • Review the topics covered in this chapter carefully Keep a copy of one or more of the suggested resource books handy for more extensive review • Don’t try to review all topics in one or two study sessions Tackle a couple of topics at a time Focus more in-depth study on the items within a topic about which you feel least confident first • Complete each group of practice questions after you study each topic, and check your answers If you experience particular difficulty with one type of question, choose similar questions from the other resources listed to practice some more • Review all the answer choices carefully before making your selection The wrong answers often give you hints at the correct one and help you confirm that you really do know the correct answer Remember that recognition is not necessarily understanding • When checking your answers to practice questions with the answer key, be sure you understand why the identified choice is the correct one Practice writing out your reasoning for choosing a particular answer and checking it against the reasoning given in the answer key • Practice pronouncing chemical terminology aloud If you can pronounce a term with ease, you are more likely to remember the term and its meaning when reading it • Review carefully the visual aspects of chemistry, such as the use of symbols, arrows, and sub- and superscripts If you know the circumstances under which particular symbols are used, you will have immediate clues to right and wrong answers • Focus on developing problem-solving skills Almost all chemical problems require the analysis, sorting, and understanding of details II Main Topics A Atoms Atomic Structure An atom is the basic unit of an element that retains all of the element’s chemical properties An atom is composed of a nucleus (which contains one or more protons and neutrons) and one or more electrons in motion around it An electron is of negligible mass compared to the mass of the nucleus and has a negative charge of –1 A proton has a mass of 1 amu (atomic mass unit) and a positive charge of +1 A neutron has a mass of 1 amu also but no charge Atoms are electrically neutral because they are made up of equal numbers of protons and electrons Dalton’s Atomic Theory In 1808, John Dalton proposed his hypotheses about the nature of matter that became the basis of Dalton’s atomic theory: • All elements are made of tiny, indivisible particles called atoms (from the Greek atomos, meaning indivisible) • Atoms of one element are identical in size, mass, and chemical properties • Atoms of different elements have different sizes, masses, and chemical properties • Chemical compounds are made up of atoms of different elements in a ratio that is an integer (a whole number) or a simple fraction • Atoms cannot be created or destroyed They can be combined or rearranged in a chemical reaction Later experiments completed the understanding of atoms: • J J Thomson discovered the electron • E Rutherford established that the atom is composed of negatively charged electrons moving in the empty space surrounding a dense, positively charged nucleus • A Becquerel and Marie Curie discovered that the decay of radioactive (unstable) nuclei resulted in the release of particles and energy Mass Number Mass number is the sum of protons and neutrons in the nucleus of an atom It varies with the isotopes of each element The mass number is indicated by the number to the upper left of the element symbol: 23Na Atomic Number Atomic number is the number of protons in the atom and is specific for each element The atomic number is indicated by the number to the lower left of the element symbol: 11Na Isotopes Isotopes are atoms of the same element that have the same number of protons (same atomic number) but different number of neutrons (different mass number) Isotopes have identical chemical properties (same reactivity) but different physical properties (for example, some decay while others are stable) The atomic weight (or mass) of an element is given by the weighted average of the isotopes’ masses Classification of Matter a Elements Elements are substances that are composed of only one type of atom Elements have chemical symbols (letters of their names) that are used for their representation in the periodic table For example, the element Helium is displayed as He In nature, atoms of one element may be chemically bonded to other atoms of the same element For example, hydrogen and oxygen are always diatomic, which means that they naturally exist as H2 and O2, respectively Elemental sulfur exists as S8 Many elements, like sodium, exist as single atoms in their elemental form b Compounds A compound is a combination of two or more atoms of different elements in a precise proportion by mass In a compound, atoms are held together by attractive forces called chemical bonds c Mixtures A mixture is a combination of two or more compounds (or substances) that interact but are not bonded chemically with one another Substances that make up a mixture can be separated by physical means Properties of Atoms Law of conservation of mass: In a chemical reaction, matter cannot be created or destroyed—i.e., the mass of the reagents always equals the mass of the products Likewise, the number of each type of atom will be equal on each side of the reaction Law of constant (definite) proportion: A chemical compound will always have the same proportion of elements by mass—e.g., water (H2O) will always be 8/9 oxygen and 1/9 hydrogen by mass Law of multiple proportions: If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers For example, 16 g of oxygen will react with 14 g of nitrogen to form NO and 28 g of nitrogen to form N2O (1:2 ratio) Questions Which of the following statements about atoms is true? a They have more protons than electrons b They have more electrons than protons c They are electrically neutral d They have as many neutrons as they have electrons What is the mass number of an atom with 60 protons, 60 electrons, and 75 neutrons? a 120 b 135 c 75 d 195 What is the atomic number of an atom with 17 protons, 17 electrons, and 20 neutrons? a 37 b 34 c 54 d 17 Two atoms, L and M, are isotopes Which of the following properties would they NOT have in common? a atomic number b atomic mass c chemical reactivity d the number of protons in the nucleus An atom with an atomic number of 58 and an atomic mass of 118 has a 58 neutrons b 176 neutrons c 60 neutrons d 116 neutrons According to Dalton’s theory, the only way a compound can consist of its elements in a definite ratio by mass is when it is made from the elements in a a definite ratio by volume b a definite ratio by number of atoms c multiple whole-number ratios by mass d multiple whole-number ratios by volume Which of the following is a mixture? a sodium chloride b rice and beans c magnesium sulfate d water The mass of an atom is almost entirely contributed by its a nucleus b protons c electrons and protons d neutrons If an atom consists of 9 protons and 10 neutrons, its a atomic number is 10 b mass number is 10 c number of electrons is 9 d electrical charge is 9 10 Which of the following is true of an atom? a It consists of protons, neutrons, and electrons b It has a nucleus consisting of protons, neutrons, and electrons c The protons are equal in number to the electrons, so the nucleus is electrically neutral d All of the above are true Answers c Atoms are electrically neutral; the number of electrons is equal to the number of protons b Mass number is the number of protons plus the number of neutrons: 60 + 75 = 135 d The atomic number is the number of protons—in this case, 17 b By definition, isotopes have different numbers of neutrons Therefore, they differ in atomic weight c The number of neutrons is equal to the atomic mass minus the atomic number (the number of protons): 118 – 58 = 60 b This is part of Dalton’s atomic theory b Rice and beans are not chemically combined and can be separated into their constituent parts by physical means a The protons and neutrons of an atom are found in the nucleus c Atoms are electrically neutral If there are 9 protons, each with a +1 charge, 9 electrons with a –1 charge are needed to balance the charge 10 a An atom consists of protons, neutrons, and electrons; the nucleus contains protons and neutrons The protons are equal in number to the electrons, but the nucleus itself is not electrically neutral B Periodic Table Periodic Law Periodic law is when the properties of the elements are a periodic function of their atomic number Periodic table is an arrangement of the elements according to similarity in their chemical properties and in order of increasing atomic number Properties of the Periodic Table a Periods Periods are the horizontal rows of the periodic table of elements Elements in the same period have the same number of electron shells (or levels) b Groups Groups are the vertical columns of elements with the same number of electrons in their outermost shell In older numbering systems using Roman numerals like the one shown above, the group number indicates the number of valence (or outermost) electrons In the current numbering system, group numbers are 1–18 from left to right and the ones place indicates the number of valence electrons Elements in the same group share similar chemical properties c Metals A metal is an element that is a good conductor of heat and electricity in addition to being shiny (reflecting light), malleable (easily bent), and ductile (made into wire) Metals are electropositive, having a greater tendency to lose their valence electrons They are grouped in the left of the periodic table (groups IA-IIA, IB-VIIIB, parts of IVA-VIA) d Nonmetals A nonmetal is an element with poor conducting properties They are electronegative and accept electrons in their valence shell They are found in the upper right-hand corner of the periodic table (group VIIA, parts of IVAVIA) e Metalloids A metalloid is an element with properties that are intermediate between those of metals and nonmetals, such as semiconductivity They are found between metals and nonmetals in the periodic table Electronic Structure of Atoms a Bohr Atom Niels Bohr’s planetary model of the hydrogen atom, in which a nucleus is surrounded by orbits of electrons, resembles the solar system Electrons could be excited by quanta of energy and move to an outer orbit (excited level) They could also emit radiation when falling to their original orbit (ground state) b Orbitals An orbital is the space where one or two paired electrons can be located These are mathematical functions (or figures) with restricted zones, called nodes, and specific shapes—for example, s orbitals are spherical; p orbitals are dumbbell-shaped c Quantum Numbers There are four quantum numbers that describe any electron in an atom They are the principle quantum number (n), the orbital quantum number (l), the magnetic quantum number (ml) and the spin quantum number (ms) ... In the reaction 2Cu2S + 3O2 2Cu2O + 2SO2, if 24 moles of Cu2O are to be prepared, then how many moles of O2 are needed? a 24 b 36 c 16 d 27 37 Which of the following equations is balanced? a 2H2O2 2H2O + O2... Which of the following equations is balanced? a Mg + N2 Mg3N2 b Fe + O2 Fe2O3 c C12H22O11 12C + 11H2O d Ca + H2O Ca(OH )2 + H2 Answers 31 c There are 2 atoms of Al, 3 atoms of C, and 9 atoms of O Look at the... If the electron configuration of an element is written 1s2 2s2 2px2 2py2 2pz2 3s1, the element’s atomic a number is 11 b number is 12 c weight is 11 d weight is 12 12 Choose the proper group of symbols for the following elements: potassium,