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What you should gain 1. An understanding of some of the principles and theories. 2. Improvement of your problem-solving skills. 3. Improvement in your scientific knowledge by understanding scientific reading. 4. Improvement in your communication and independent learning skills. Resources for YOU You need to keep track of how you are doing in the class and take action if you fall behind or have trouble with the material. A. Fellow students - meet others in the class. Even though you and the other student may be perplexed about a subject, you will find that talking together in the language of chemistry may help you out of a trouble. B. Your instructor(s) - I am especially willing to answer questions in class, and I am available most of the working week (10am - 5:30 pm) in my office or on the 4th floor of Lappin to answer questions if I don't have a class. Your lab instructor (if you have a different one) or indeed any of the chemistry faculty are usually willing to help out if you need help. C. Tutors are available. One or more may be available on the second floor of Allie Young (783-5200). Book tutors early as they tend to be booked up by the second week of the semester. Why Chemistry ???? Consider these: Pain Killers Morphine – Analgesic extracted from the opium plant. Reacts with receptors in the brain, and reduces the sensation of pain. Heroine – Illegal drug with effects similar to morphine, but considerably more addictive. Codeine – Also used as a pain killer, but with 1/10 the potency of morphine. Thebaine – Similar to codeine, with one exception, it causes convulsions if ingested. Chemical formula and structure HO O O Morphine O N O H O O O Codeine N O H HO Heroine Thebaine O O N N HO H O H Chapter One Matter and Life The Central Science Chemistry is often referred to as “The Central Science” because it is crucial to all other sciences. Matter: Anything that has mass and occupies space – things you can see, touch, taste, or smell. Property: a characteristic that can be used to describe a substance. Size, color, temperature are most familiar properties of matter. Chemical composition Chemical Reactivity Physical Change: Does not alter the chemical makeup of a substance. Change is reversible. Melting of solid ice is a physical change. Chemical Change: Alters chemical makeup of a substance. Change is irreversible. Rusting of iron is a chemical change. Here, iron combines with oxygen and produces a new substance rust. States of Matter Solid: A substance that has a definite shape and volume. Liquid: A substance that has a definite volume but that changes shape to fill the container. Gas: A substance that has neither a definite volume nor a definite shape. Many substances, such as water, can exist in all three states depending on the temperature. The conversion of a substance from one state into another is known as change of state. The three states Solid state Liquid state Gaseous state Classification of Matter Pure Substance: Uniform in its chemical composition and properties. Sugar and water are pure substances. Mixture: Composition and properties may vary. Different amounts of sugar dissolved in water will determine sweetness of water. Sugar water is an example of a mixture. Chemical Compounds: Substance that can be broken down into simpler substances. Element: Substance that can not be brokendown chemically into simpler substances. The classification of matter Fig. 1.4 Chemistry is a science that describes Physical properties Composition Structure Reactions of Matter Matter: Anything that has mass and occupies space – things you can see, touch, taste, or smell. Property: a characteristic that can be used to describe a substance. Size, color, temperature are most familiar properties of matter. Physical Change: Does not alter the chemical makeup of a substance. Change is reversible. Melting of solid ice is a physical change. Chemical Change: Alters chemical makeup of a substance. Change is irreversible. Rusting of iron is a chemical change. Here, iron combines with oxygen and produces a new substance rust. Classification of Matter Pure Substance: Uniform in its chemical composition and properties. Sugar and water are pure substances. Mixture: Composition and properties may vary. Different amounts of sugar dissolved in water will determine sweetness of water. Sugar water is an example of a mixture. Chemical Compounds: Substance that can be broken down into simpler substances. Element: Substance that can not be brokendown chemically into simpler substances. States of Matter Solid: A substance that has a definite shape and volume. Liquid: A substance that has a definite volume but that changes shape to fill the container. Gas: A substance that has neither a definite volume nor a definite shape. Many substances, such as water, can exist in all three states depending on the temperature. The conversion of a substance from one state into another is known as change of state. The three states The classification of matter Fig. 1.4 Chemical Elements and Symbols 113 Elements are known until today. Only 90 of these elements occur naturally, remaining are produced artificially by chemists and physicist. Some familiar elements are iron, tin, carbon, oxygen, hydrogen, sulfur, etc. Some unfamiliar elements are niobium, rhodium, thulium, californium etc. Each element has its own unique symbol. – One or two letter symbols are used to represent elements. – First letter is always capitalized and the second letter is always a lower case. – All naturally occurring elements are not equally abundant. Oxygen and silicon together constitute 75% of the earth’s crust. Chemical Formula: A notation for chemical compound using element symbols and subscripts to show how many atoms of each element are present. The formula for water is H2O. H2O indicates that two hydrogen and one oxygen combined together to produce water. When no subscript is given for an element a subscript of ‘1’ is understood. Water Methane Amino acid O H O H H H2O H2N C H CH C OH H H CH4 CH3 C3H7NO2 2 H atoms 4 H atoms 7 H atoms 1 O atom 1 C atom 3 C atoms 1 N atom 2 O atoms Elements and the Periodic Table •Periodic Table, is a representation of 113 elements in a tabular format. Metals: 89 of the 113 elements appear on the left side of the Periodic Table. Some common properties of metals are: Solid at room temperature (except mercury which is a liquid) Good conductor of heat Good conductor of electricity Malleable. Nonmetals: Appears on the right side of the Periodic Table. 17 elements are nonmetals. Nonmetals are poor conductor of heat and electricity. Out of these 17 nonmetal elements – Eleven are gases at room temperature (H, N, O, etc.) – Five are solids (sulfur) – One is a liquid (bromine). •Metalloids: Appears between metals and nonmetals on the periodic table. Their properties are between metals and nonmetals. Boron, silicon, arsenic are examples of some of the metalloids. Lecture 3 Chapter Summary •Chemistry is the study of matter. •Matter is anything that has mass and occupies space. •Physical change does not alter the chemical makeup of a substance. Change is reversible. •Chemical change alters chemical makeup of a substance. Change is irreversible. •Pure substances have uniform chemical composition and properties. Composition and properties of a mixture may vary. • • •Substance that can be broken down into simpler substances is a chemical compound. • •Substance that can not be broken down chemically into simpler substances is known as an element. • •Elements symbols. are represented by one or two letter Elements and the Periodic Table •Periodic Table, is a representation of 113 elements in a tabular format. • Chemical Formula is a notation for chemical compound to show how many atoms of each element are present. • H 2O • •Elements are roughly divided into 3 groups – Metals – Nonmetals – Metalloids Chapter Three Atoms and the Periodic Table Atomic Theory •1. All Matter is composed of atoms. •2. The atoms of a given element differ from the atoms of all other elements. •3. Chemical compounds consist of atoms combined in specific ratios (formulas). •4. Chemical reactions change only the way the atoms are combined in compounds; the atoms themselves are unchanged. • • • • Atoms are composed of tiny subatomic particles called protons, neutrons, and electrons. Name Proton Neutron Electron Symbol p n e- (grams) 1.672622 x 10-24 1.674927x10-25 9.109328x10-28 (amu) 1.007267 1.008665 5.485799x10-4 Charge +1 0 -1 Since the masses of atoms and their constituent subatomic particles are so small when measured in grams that their masses are expressed on a relative mass scale. The basis for the relative atomic mass scale is an atom of carbon that contain 6 protons and 6 neutrons. This carbon atom is assigned a mass of exactly 12 atomic mass unit (amu). • Both a proton and a neutron have mass of 1 amu. Hydrogen atoms have mass of 1 amu, oxygen atoms have mass of 16 amu, etc. • Subatomic particles are not randomly throughout an atom. • The protons and neutrons are held together closely in a dense core called the nucleus. • Surrounding the nucleus, the electrons move about rapidly through a large, mostly empty volume of space. distributed • • Diameter of a nucleus is only about 10-15 m . Diameter of an atom is only about 10-10 m . Fig 3.1 The structure of an atom The structure of the atom is determined by an interplay of different attractive and repulsive forces. • Unlike charges attract each other - the negatively charged electrons are held close to the nucleus due to this attraction. • Like charges repulse each other - two negatively charged electrons try to get as far away as possible occupying large volume in space. The Positively charged protons in the nucleus also repel each other, however, they are held together by a unique attraction called nuclear strong force. • Question 3.39 • How many Na atoms of mass 22.99amu are in 22.99g of sodium. • 1amu = 1.660539 x 10 -24 g • 22.99g x ________1amu atom • 1.660539 x 10-24g amu x Na 22.99 Lecture 4 and into lecture 5-6 Element and Atomic Number •Atomic Number (Z): Number of protons each atom of different elements contain in their nucleus. We can identify the element if we know the number of protons in the nucleus. •Mass Number (A): The total number of protons and neutrons in an atom. Isotopes and Atomic Weight •Isotopes: Atoms with identical atomic numbers (Z) but different mass numbers (A) are called isotopes. Hydrogen, deuterium, and tritium are three isotopes of hydrogen. • - Most abundant hydrogen isotope has one proton and no neutron (A=1); • - deuterium isotope has one proton and one neutron (A=2), and • - tritium isotope has one proton and two neutrons (A=3). Isotopes of hydrogen •Atomic Weight: The weighted average mass of an element’s atoms in a large sample that includes all the naturally occurring isotopes of that atom. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Isotope Table Element Mass Abundance Arsenic Carbon Chlorine Isotope Natural Accurate 75As 12C 13C 74.92160 12.000000 13.003355 35Cl 34.968852 37Cl Fluorine Hydrogen 19F 1H Nitrogen 18.998403 1.007825 14N 14.003074 16O Silicon Silver Sodium Sulfur Tin 99.63% 15.994915 23Na 0.37% 99.76% 16.999131 17.999160 30.973762 81.916698 27.976927 28.976495 29.973770 106.905092 108.904757 22.989767 32S 33S 34S 112Sn 114Sn 115Sn 116Sn 117Sn 118Sn 119Sn 120Sn 122Sn 124Sn 0.015% 100.00% 5.80% 91.72% 2.20% 15.000108 17O 18O 31P 82Se 28Si 29Si 30Si 107Ag 109Ag Phosphorus 24.23% 100.00% 99.985% 2.014102 126.904473 53.93961 55.93494 56.93540 15N Oxygen 75.77% 36.965903 2H 127I 54Fe 56Fe 75Fe Iodine Iron 100.00% 98.90% 1.10% 0.04% 0.20% 100.00% 8.74% 92.23% 4.67% 3.10% 51.839% 48.161% 100.00% 31.972070 32.971456 33.967866 111.904826 113.902784 114.903348 115.901747 116.902956 117.901609 118.903310 119.90220 121.903440 123.905274 95.02% 0.75% 4.21% 0.97% 0.65% 0.36% 14.53% 7.68% 24.22% 8.58% 32.59% 4.63% 5.79% From "The CRC Handbook of Chemistry and Physics", 73rd Edition, D. R. Lide, Ed., CRC Press, Ann Arbor, MI, 1992 - Periodic Table •Fig 3.2 The periodic table 3.4 The Periodic Table • • Beginning at the upper left corner of the periodic table, elements are arranged by increasing atomic number into seven horizontal rows, called periods, and 18 vertical columns, called groups. The elements in a given group have similar chemical properties. Lithium, sodium, potassium and other elements in group 1A have similar properties. Similarly, chlorine, bromine, iodine, and other elements in group 7A behaves similarly. •The table has 113 boxes, each of which tells the symbol, atomic number, and atomic weight of an element. The first period contains only 2 elements. The second and third periods each contains 8 elements. The fourth and fifth periods each contains 18 electrons. The sixth period contains 32 electrons The seventh period, incomplete yet, contains 27 elements. •Main Groups: The two large groups on the far left and the six on the far right are called the main groups. •Lanthanides: 14 elements following lanthanum in group 6. •Actinides: 14 elements following actinium in group 7. •Transition Metal Groups: Elements in the groups numbered 1B through 8B. •Inner Transition Metal Groups: The 14 groups shown separately at the bottom of the table and are not numbered. 3.5 Some Characteristics of Different Groups • • Various elements in a given group of the periodic table show remarkable similarities in their properties. For example, Group 1A – Alkali metals: Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr) are shiny, soft, and low melting metals. All reacts rapidly with water to form products that are highly alkaline or basic-hence the name alkaline metals. • Group 2A – Alkaline earth metals: Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) are lustrous,, silvery metals. They are less reactive than their neighbors. • Group 7A - Halogens: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and astatine (At) are colorful and corrosive nonmetals. All are found in nature in combination with other elements, such as with sodium in sodium chloride (NaCl) • Group 8A-Noble gases: Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) are colorless gases of very low chemical reactivity. 3. 6 Electronic Structure of Atoms • • • Quantum mechanical model of atomic structure: Electrons are not perfectly free to move about in an atom. Each electron is restricted to moving about only in a certain region of space within the atom, depending on the amount of energy the electron has. • • • • Different electrons have different amounts of energy and thus occupy different regions within the atom. The energies of electrons are quantized, or restricted to having only certain values. The electrons in an atom are grouped around the nucleus into shells. Within the shells, electrons are further grouped into subshells of four different types, identified as s, p, d, and f in order of increasing energy. • The first shell has only an s subshell • The second shell has an s and a p subshell • The third shell has an s, a p, and ad subshell. • The fourth shell has an s, a p, a d, and an f subshell. • • • The number of subshells in a given shell is equal to the shell number. For example, shell number 3 has 3 subshells. Within each subshell, electrons are further grouped into orbitals, regions of space within an atom where the specific electrons are more likely to be found. There are different number of orbitals within the different kinds of subshells. Different orbitals have different shapes. Orbitals in s subshells are spherical (a), while orbitals in p subshells are roughly dumbbell shaped (b). • • • • The first shell (nearest to the nucleus) can hold only 2 electrons. They are in a single 1s orbital. The second shell can hold 8 electrons – 2 in a 2s orbital and 6 in 3 2p orbitals. The third shell can hold 18 electrons – 2 in a 3s orbital, 6 in 3 3p orbitals, and 10 in 5 3d orbitals. The fourth shell can hold 32 electrons – 2 in a 4s orbital, 6 are in 3 4p orbitals, 10 are in 5 4d orbitals, and 14 are in 7 4f orbitals. •The overall electron distribution within an atom is summarized in table 3.2 shown below. 3.7 Electron Configuration • Electron Configuration: The exact arrangement of electrons in atom’s shells and subshells. Rules to predict electron configuration: 1. Electrons occupy the lowest-energy orbitals available, beginning with 1s and continuing in order shown in the fig. 3.5. 2. Each orbital can hold only two electrons, which must be oppositely spin. 3. Two or more orbitals with the same energy – each orbital gets one electron before any orbital gets two. •Electrons fill orbitals in energy orbitals upward. numbered shells fill However, some overlap the third energy level. Fig 3.5 order of orbital energy levels ascending order, from the lowestGenerally, this means that lowerbefore higher-numbered shells. in energy levels occurs starting in •Electronic configuration of a few elements are shown below: 3.8 Electron Configuration and the Periodic table •The periodic table can be divided into four regions or blocks, of elements according to the shells and subshells as shown in Fig 3.6. •Valence Shell : Outermost shell of an atom. •Valence electrons: An electron in an outermost shell of an atom. These electrons are loosely held, they are most • Fig 3.6 electron configurations and the periodic table Chapter Summary • • All matter is composed of atoms. An atom is the smallest and simplest unit into which an element can be divided while maintaining the properties of the element. • Atoms are made up of subatomic particles called protons, neutrons and electrons. Protons have positive, electrons have negative, and neutrons have zero electrical charges. • Elements differ from each other according to the number of protons their atoms contain (Atomic number, Z) Chapter Summary Contd. • Mass number (A): Total number of protons and neutrons in an atom. • Isotopes: Atoms with identical number of protons but different numbers of neutrons. • Periodic table: Tabular arrangement of elements according to their valence shells. • The electrons surrounding an atom are grouped into shells. Within each shell, electrons are grouped into subshells, and within subshells into orbitals – regions of space where electrons are more likely to be found. Chapter Summary Contd. • s orbitals are spherical and p orbitals are bumbbell shaped. • Each orbital and each shell can hold a specific number of electrons. •- The first shell can hold only two electrons. 2 electrons in an s orbital (1S2). •- The second shell can hold 8 electrons. 2 electrons in an s orbital and 6 electrons in 3 p orbitals. (2S2 2p6). •- The third shell can hold 18 electrons. 2 electrons in an s orbital, 6 electrons in 3 p orbitals, and 10 electrons in 5 d orbitals (3S2 3p6 3d10); and so on.