1 2.1 Matter Matter is anything that has mass and occupies space. Matter is anything that has mass and occupies space. 4 States of Matter 4 States of MatterSolidLiquid Gas Gas Plasma Plasma

2 Matter usually exists as: A. pure substances - elements – one type of atom - compounds – two or more types of atoms B. mixtures - homogeneous – 1 phase - heterogeneous – >1 phase

3 Mixtures Have variable composition and can be either homogeneous or heterogeneous Have variable composition and can be either homogeneous or heterogeneous Homogeneous mixtures are called SOLUTIONS. Homogeneous mixtures are called SOLUTIONS.

4 Solutions Solution – homogenous mixture Solution – homogenous mixture A solution is not necessarily a liquid. Can be gas or solid. A solution is not necessarily a liquid. Can be gas or solid.

5 Pure Substances Element – can not be decomposed into simpler substances Element – can not be decomposed into simpler substances Composed of atoms Composed of atoms Compound – has definite composition of elements Compound – has definite composition of elements

6 Changes of State and Properties Physical changes – does not change composition of compound Physical changes – does not change composition of compound Chemical changes – converts to a different substance Chemical changes – converts to a different substance Intensive Properties – independent of amt. Intensive Properties – independent of amt. Extensive Properties – dependent on amt. Extensive Properties – dependent on amt.

7 2.1Elements and Symbols

8  Elements are pure substances that cannot be separated into simpler substances by ordinary laboratory processes.  Elements are the building blocks of matter.  There are 113 elements known today. gold carbon aluminum Elements

9 Sources of Some Element Names

10  Every element has a symbol that represents its name.  Symbols consist of 1 or 2 letters.  Only the first letter in a symbol is capitalized. Examples: 1-Letter Symbols 2-Letter Symbols C carbon Co cobalt N nitrogenCa calcium F fluorine Al aluminum O oxygen Mg magnesium Symbols of Elements

11 Several symbols are derived from Latin names. Several symbols are derived from Latin names. Some examples are shown below: copper, Cu (cuprum) gold, Au (aurum) iron, Fe (ferrum) silver, Ag (argentum) Some examples are shown below: copper, Cu (cuprum) gold, Au (aurum) iron, Fe (ferrum) silver, Ag (argentum) Symbols from Latin Names

12 Carbon, oxygen, and hydrogen are the most abundant elements in the human body. Carbon, oxygen, and hydrogen are the most abundant elements in the human body. Elements in the Body

13  The physical properties of an element are the characteristics that can be observed without changing the substance. Physical Properties

14 2.2The Periodic Table

15 The periodic table arranges elements according to similar properties. Periodic Table

16 On the periodic table, each vertical column is called a group of elements. On the periodic table, each vertical column is called a group of elements. A group contains elements with similar chemical and physical properties. A group contains elements with similar chemical and physical properties. Each group is identified by a group number at the top of the column. Each group is identified by a group number at the top of the column. The representative elements have group numbers of 1A – 8A. The transition elements use the letter “B.” The representative elements have group numbers of 1A – 8A. The transition elements use the letter “B.” Groups on the Periodic Table

17 Groups and Group Numbers

18 Numbering Groups One numbering system for groups assigns the letter A to the representative elements and the letter B to the transition elements. One numbering system for groups assigns the letter A to the representative elements and the letter B to the transition elements. Another system assigns the numbers 1-18 to the columns across the periodic table. Another system assigns the numbers 1-18 to the columns across the periodic table.

19 Group Numbers Group numbers

20 Several groups of representative elements are classified by name. Several groups of representative elements are classified by name. Group 1AAlkali Metals Group 2AAlkaline Earth Metals Group 7A Halogens Group 8ANoble Gases Representative Elements

21 Names of Some Representative Groups

22 Group 1A, the Group 1A, the alkali metals, includes sodium, lithium, and potassium. Group 7A, the halogens, Group 7A, the halogens, includes chlorine, bromine, and iodine. Representative Elements

23 On the periodic table, each horizontal row is called a period. On the periodic table, each horizontal row is called a period. A period is identified by a number such as 1, 2, 3, or 4. A period is identified by a number such as 1, 2, 3, or 4. Periods 2-7 include representative elements and transition elements. Periods 2-7 include representative elements and transition elements. Periods on the Periodic Table

24 Location of Periods Period 4

25 NONMETALS METALOIDS Metals, Nonmetals, and Metalloids METALS

26  Metals  Are located to the left of the heavy line.  Are shiny, ductile, and good conductors.  Metalloids  Are elements along the heavy line.  Have properties of both metals and nonmetals.  Nonmetals  Are located to the right of the heavy line.  Are dull, brittle, poor conductors, and good insulators. Metals and Nonmetals

27 Comparing A Metal, Metalloid, and Nonmetal

The Atom

29  Matter is composed of tiny particles called atoms.  Atoms in each element are similar and different from atoms of other elements.  Atoms of two or more different elements combine in simple ratios to form compounds.  A chemical reaction involves changes in the arrangements of atoms. Atomic Theory

30 Subatomic Particles  Chemists are interested in three particles in atoms: protons, electrons, and neutrons.  Protons have a positive (+) charge; electrons have a negative (-) charge.  Like charges repel and unlike charges attract.

31 Summary of Subatomic Particles

32 Rutherford’s Gold-Foil Experiment  Most positive particles aimed at atoms of gold went straight through the atoms. Only a few were deflected.  Rutherford concluded that atoms have a small, dense nucleus with a positive charge.

33  An atom consists of a nucleus and a cloud of electrons.  The nucleus contains all of the protons and neutrons.  The rest of the atom, which is mostly empty space, is occupied by the electrons. Structure of the Atom

34  The atomic number is equal to the number of protons in an atom.  On the periodic chart, the atomic number appears above the symbol of an element. 2.4 Atomic Number and Mass Number 11 Na Atomic Number Symbol

35 Atomic Numbers and Protons for Lithium and Carbon Atoms

36  An atom is electrically neutral; the net charge is zero.  In an atom, the number of protons is equal to the number of electrons. # protons = # electrons  Therefore, the atomic number is also equal to the number of electrons in a neutral atom. Electrons in An Atom

37  The mass number gives the total number of protons and neutrons in the nucleus. Mass number = # protons + # neutrons Mass Number

38  The atomic symbol represents a particular atom of an element.  The atomic symbol shows the mass number in the upper left corner and the atomic number in the lower left corner.  For example, an atom of sodium with atomic number 11 and a mass number 23 has the following atomic symbol: mass number 23 Na atomic number 11 Atomic Symbol

39  When we know the atomic symbol of an atom, we can determine the number of protons (p + ), neutrons, (n), and electrons (e - ) O P Zn O P Zn p + 15 p + 30 p + 8 n16 n35 n 8 e - 15 e - 30 e - Information from Atomic Symbols

Isotopes and Atomic Mass 24 Mg 25 Mg 26 Mg

41  Isotopes are atoms of the same element that have different mass numbers.  Isotopes have the same number of protons, but different numbers of neutrons.  Most elements have two or more isotopes. Isotopes

42 Isotopes of Magnesium In naturally occurring atoms of magnesium, there are three isotopes. 24 Mg makes up 78.9% of magnesium atoms. 24 Mg makes up 78.9% of magnesium atoms. 25 Mg makes up 10.0% and 26 Mg makes up 11.1%. 25 Mg makes up 10.0% and 26 Mg makes up 11.1%. 24 Mg 25 Mg 26 Mg

43  Atomic mass is the weighted average mass of all the isotopes of that element.  The atomic mass of each element is compared to 12 C, which a mass of 12 amu.  The atomic mass of each element is listed below the symbol of the element on the periodic table. Atomic Mass

44 Atomic Mass of Magnesium  The individual atomic masses of all the isotopes contribute to the atomic mass of Mg.  As a weighted average, the atomic mass is not a whole number.

45 To calculate atomic mass, use the percent(%) abundance of the isotopes and the mass of each isotope of that element. mass isotope(1) x (%) + mass isotope (2) x (%) + … Calculating Atomic Mass

46 Atomic Mass for Cl  The atomic mass of chlorine is the weighted average of two isotopes 35 Cl and 37 Cl.

47 Cl-35 is 75.8 % and Cl-37 is 24.2% of natural chlorine. Cl-35 is 75.8 % and Cl-37 is 24.2% of natural chlorine. Using the given atomic mass of each isotope, calculate the contribution of each isotope to the atomic mass of Cl x 75.8 = x 24.2 = Using the given atomic mass of each isotope, calculate the contribution of each isotope to the atomic mass of Cl x 75.8 = x 24.2 = Add together = = atomic mass Cl Add together = = atomic mass Cl Calculating Atomic Mass for Chlorine

48 Isotopes of Some Elements and Their Atomic Mass

Electron Energy Levels

50 Electromagnetic Radiation Electromagnetic radiation Consists of energy particles called photons that travel as waves. Consists of energy particles called photons that travel as waves. Includes low energy particles that have long wavelengths and high energy particles that have short wavelengths. Includes low energy particles that have long wavelengths and high energy particles that have short wavelengths.

51 Electromagnetic Spectrum

52  Electrons are arranged in specific energy levels called shells.  The first energy level (n=1) contains electrons that have the lowest energy.  The energy levels are labeled 1, 2, 3, and so on. Electron Energy Levels

53  Electrons of similar energy are grouped in energy levels.  The maximum number of electrons in any energy level is equal to 2n 2. n = 12(1) 2 = 2 n = 22(2) 2 = 8 n = 32(3) 2 =18 n = 42(4) 2 =32 Number of Electrons

54 The order in which electrons enter and fill the shells for the first 20 electrons is The order in which electrons enter and fill the shells for the first 20 electrons is Shell number e8e8e2e Although shell 3 can eventually hold 18 electrons, it fills to 8 first. Although shell 3 can eventually hold 18 electrons, it fills to 8 first. Order of Electron Filling

55  In the electron shell arrangement, the electrons in each shell of an atom are listed in order of increasing energy. Element Shell 1 23 He2 F2 7 Ne2 8 Al2 83 Cl28 7 Electron Shell Arrangement

56

57 All the elements in a group have the same number of electrons in their outermost shells. All the elements in a group have the same number of electrons in their outermost shells. Elements in a group have similar chemical and physical properties. Elements in a group have similar chemical and physical properties. Example: Group 2 Be2, 2 Mg 2, 8, 2 Mg 2, 8, 2 Ca 2, 8, 8, 2 Periodic Law

58 Energy Level Changes  Electrons are in discrete energy levels.  An electron absorbs energy to “jump” to a higher energy level.  When an electron falls to a lower energy level, energy is emitted.  In the visible range, the emitted energy appears as a color. 2.6 Electron Energy Levels

Subshells and Orbitals

60  Within each energy level, electrons are grouped into energy sublevels or subshells.  All electrons in a subshell have the same energy.  The different subshells are designated by the letters s, p, d, f. Subshells

61 Number of Subshells in a Shell  The number of subshells in each shell is the same as the shell number. Shell Number ofTypes of Number Subshells Subshells n=444s, 4p, 4d, 4f n=333s, 3p, 3d n=222s, 2p n=111s

62 Energy Levels of Subshells  The s subshell has the lowest energy in any shell followed by the p, d, and f subshells. 3d n = 33p 3s 2p 2s n = 11s n = 2

63  An orbital is a 3 dimensional space around a nucleus in which an electron is most likely to be found.  The shape represents electron density (not a path the electron follows).  Each orbital can hold up to 2 electrons. Orbitals

64 Subshells and Orbitals Each subshell has a specific number of orbitals.  Each s subshell contains one s orbital.  Each p subshell contains three p orbitals.  Each d subshell contains five d orbitals.  Each f subshell contains seven f orbitals.

65 s and p Orbitals  In an atom, all the orbitals are centered around the nucleus. For example, the illustration of the combination of s and p orbitals is

66 Electrons in Each Subshell

Electron Configurations

68  An electron configuration:  Is a list of the subshells and the number of electrons in each in order of increasing energy.  Contains superscripts that give the number of electrons in each subshell.  Of neon is as follows: number of electrons in each subshell 1s 2 2s 2 2p 6 Electron Configuration

69 Subshell Location on the Periodic Table The periodic table contains subshell blocks arranged in order of increasing energy. The periodic table contains subshell blocks arranged in order of increasing energy.

70 There is a specific number of electrons in each subshell block. There is a specific number of electrons in each subshell block. 1 s 1 s 2 p 1 p 2 p 3 p 4 p 5 p d 1 - d f 1 - f 14 Subshell Blocks

71 An electron configuration is written by:  Locating the element on the periodic table.  Starting with H and writing each subshell notation and electrons in order. Groups 1-2 = s level Groups 3-8= p level Groups 3-8= p level Transition= d level Transition= d level Lanthanides/Actinides = f level Writing an Electron Configuration

72 First Period H1s 1 He 1s 2 Second Period Li 1s 2 2s 1 C1s 2 2s 2 2p 2 Third Period Na1s 2 2s 2 2p 6 3s 1 Al1s 2 2s 2 2p 6 3s 2 3p 1 S1s 2 2s 2 2p 6 3s 2 3p 4 Some Electron Configurations

73 Electron Configurations for Atomic Numbers 1-18

74 Electron Configurations for Elements 19-36

75 Noble Gas Notation A noble gas notation is used to abbreviate the completed subshells as [noble gas]. A noble gas notation is used to abbreviate the completed subshells as [noble gas]. For example, the complete configuration of bromine is For example, the complete configuration of bromine is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Ar configuration Ar configuration The noble gas notation for bromine is The noble gas notation for bromine is [Ar] 4s 2 3d 10 4p 5 [Ar] 4s 2 3d 10 4p 5

76 Group Numbers and Subshells The Group Number is the sum of the s and p electrons in the outermost shell. The Group Number is the sum of the s and p electrons in the outermost shell.