CHEM 121 Chapter 2 Winter

Elements and Symbols Elements: Chemical symbols Ex. cobalt = nitrogen = 2

Elements Ordered by atomic number “Periodic” trends Periodic table by Mendeleev (1871) 1A2A 3B4B5B6B7B 8B 1B2B 3A4A5A6A7A 8A 3

Some unusual element symbols Au Ag Fe Pb Cu 4 Sn K Na

Reading the Periodic Table Period: Group: Alkali metalsAlkali metals: Alkaline earth metals: Halogens: 5 Noble Gases:

Metals, Nonmetals, and Metalloids Metals: Nonmetals: Metalloids: B, Si, Ge, As, Sb, Te, At 6

Carbon Three elemental forms Interesting bonding with many elements 7 DiamondGraphiteBuckyball

Element Song Meet the elements: e=related All of the elements: wSKFBpo&feature=related 8

Elements of Life 9 CNOHCNOH

Other life elements Fluids: Na K Cl 10 Major minerals (macronutrients) Proteins: Mg S Teeth & Bone: Ca P Trace elements (micronutrients) FeZn IFSe

Molecules Molecules: Compounds: Chemical formula: How many atoms? NaCl H 2 O CsCl 2 H 2 O 2 Ca(OH) 2 11

How many of each type of atom is in one molecule of ammonium phosphate? 12 3-minute practice

Atoms and Subatomic Particles ProtonNeutronElectron Diameter of one atom: 0.1 – 0.5 nm 13 amu: atomic mass unit (1/12 C atom mass) Charge Mass (g) Mass (amu) Location

Atomic Number and Mass Number Atomic Number (Z) 14 Atoms are electrically neutral Mass Number (A)

How many protons, electrons, and neutrons are in each of the following: Z = 14A= 29 An atom with a nucleus with 4 protons and 5 neutrons? A potassium atom with a mass number of 39? 15 3-minute practice

Isotopes Isotopes: 16 Mg Atomic Symbol

Isotopes of Carbon 12 C : 6 protons + 6 neutrons 13 C : 6 protons + 7 neutrons 14 C : 6 protons + 8 neutrons % 1.11 % <0.01 % All have nearly identical chemical behavior

How many protons, neutrons and electrons does each of the following have? 35 Cl 37 Cl C minute practice

Atomic Mass weighted average of masses of all the naturally occurring isotopes of that element 19 Example: chlorine 35 Cl 37 Cl Mass (amu)x Abundance (%) Contribution to average Cl atom = x x = =

Relative Masses of Atoms Atoms are too small to measure actual mass Compare masses of atoms using relative mass 20 An average Zn atom is ~ 3x more massive than an average Na atom

Medical Use of Isotopes I

Reading the Periodic Table Period: horizontal rowGroup: vertical column Elements in the same group have similar chemical properties because they have the same number of outer shell e - 22 Each e - in an atom “sits” at an energy level (n)

Energy States Ground state: n = 1 Excited states: n = 2, 3, 4,… Photon emitted: Photon absorbed: 23

Energy Sublevels Each level consists of sublevels # of sublevels in each level = level number n = 1  n = 2  n = 3  n = 4  24 Increasing energy of sublevels within an energy level:

Disneyland Analogy 25

Orbitals Regions with the highest probability of finding an electron Each type of orbital has a given shape: 26 s orbital p orbitals

Orbitals 27 d orbitalsEach orbital can hold _____ electrons s orbitals: p orbitals: d orbitals:

Orbitals f orbitals int.ch.liv.ac.uk/Lanthanide/Ln_Chemistry_folder/ int.ch.liv.ac.uk/Lanthanide/Ln_Chemistry_folder/Miscellaneous%20folder/Miscellaneous.html#f_orbitals 28

How many sublevels are in the n = 3 energy level? What are these sublevels? How many of each type are there? How many electrons can be held in the n = 3 energy levels? 29 5-minute practice

Orbital Energy Levels Pauli Exclusion Principle: Electrons want to sit in lowest energy level For a given n value: Order of sublevel energy : s < p < d < f Orbital Diagrams 30

1s Orbital Diagram: Electron Configurations 31 tell us which orbitals electrons are in for a given atom Example: HydrogenAtomic Number: (How many electrons?) Electron Configuration:

1s Orbital Diagram: Electron Configurations 32 Example: HeliumAtomic Number: (How many e-?) Electron Configuration: 1s Orbital Diagram: Example: Lithium Atomic Number: (How many e-?) Electron Configuration: 2s

1s Orbital Diagram: Electron Configurations 33 Example: BoronAtomic Number: (How many electrons?) Electron Configuration: 2s 2p

1s Orbital Diagram: Electron Configurations 34 Example: OxygenAtomic Number: (How many electrons?) Electron Configuration: 2s 2p Abbreviated Configuration:

Electron Configurations relate to the Periodic Table! s block elements: end with s orbital Na: p block elements: end with p orbitals P: d block elements: end with d orbitals Ni: Note: 4s orbital comes before 3d orbital 35

Sublevel Order 36

Write the abbreviated electron configuration for the following: K S Br Ar Cs 37 5-minute review

Periodic Trends Valence electrons: 38 Boron (B):How many valence electrons?

Chlorine (Cl): Periodic Trends 39 Aluminium (Al): How many valence electrons?

Electron Dot Symbols 40 LithiumValence electrons? CarbonValence electrons? FluorineValence electrons?

Draw electron dot symbols for the following: Sulfur Potassium Beryllium Silicon 41 5-minute review

Elements Elements ordered by atomic number “Periodic” trends Periodic table by Mendeleev (1871) 1A2A 3B4B5B6B7B 8B 1B2B 3A4A5A6A7A 8A 42

Atomic radius: Atomic Size 43

Ionization: Ionization Energy 44