Chemistry – Nov 28, 2018 P3 Challenge- Objective – Pick up 4 handouts Name an alkali metal. Name a transition metal. Name a halogen. Objective – Periodic Properties Atomic Structure Pick up 4 handouts

Chemistry – Nov 28, 2018 Objective – Periodic table: Properties Atomic Structure / Bohr Model Atomic Structure / Quantum Mechanics Assignment: Bohr Model Worksheet, Atomic Structure Worksheet Agenda Periodic properties (handout) Metals/nonmetals (handout) More about elements (handout) Atomic Structure overview Bohr Model Orbital Shapes Atomic Structure Quantum Numbers

Elements within a Group share Chemistry – Periodic Law Alkali metals (Group 1) are soft enough to cut with a butter knife, react with water, form strong bases Alkaline earth metals (Group 2) are similar to alkali but less reactive with water and harder. They also form strong bases. The halogens (Group 17) form diatomic molecules and vary in states down the group from gases to solids. They are nonmetals and react with metals to form salts. They react with water to form acids. The noble gases (Group 18) are unreactive and exist as gases.

Metals / Nonmetals / Metalloids Differences between metals and nonmetals tend to revolve around these properties. Metalloids have some properties from both lists.

States of the elements Everything on this slide is a memory item. Most elements are solids. There are two liquids: Br2 and Hg There are 11 gases: H2, N2, O2, F2, Cl2 , He, Ne, Ar, Kr, Xe, Rn There are 9 molecular elements H2, N2, O2, F2, Cl2 , Br2, I2, S8, P4 All others exist as individual atoms.

Distribution of elements in nature 98 naturally occurring elements (1 – 98) 93 – 98 only in small amount added recently, so most people say 92 60 elements used in the human body 6 most common make up 99%: O (65%), C(18%), H(10%), N, Ca, P 5 significant ones make up 0.85%: K, S, Na, Cl, Mg Trace others: Fe, F, Zn, Si, Rb, Sr, Br, Pb, Cu Al, Cd, Ce, Ba, Sn, I, Ti, B, Se, Ni, Cr, Mn, As, Li, Hg, Cs, Mb, Ge, Co, Sb, Ag, Nb, Zr, La, Te, Ga, Y, Bi, Tl, In, Au, Sc, Ta, V, Th, U, Sm, W, Be, Ra Most abundant in universe: H (74%), He (24%) Most abundant for earth: Fe (32%), O(30%), Si(15%), Mg(14%), S, Ni, Ca, Al Most abundant for earth’s crust: O(47%), Si(28%), Al(8%), Fe(5%), Ca, Na, K, Mg

Review Atomic models Recall the Nuclear model and where subatomic particles are located Recall the Bohr model that uses quantized orbits Recall Quantum Mechanics that uses quantized orbitals Orbitals that we draw represent a 95% probability of finding an electron in that space. Any single orbital can contain up to two electrons (0, 1, or 2)

Bohr Model Based on x ray spectra line data Electrons located in nested shells located in specific quantized orbits Shells given labels from Xray spectra: K, L, M, N. Each shell can hold only a given number of electrons: K – 2 electrons L – 8 electrons M – 18 electrons N – 32 electrons The build an atom app used an unlabeled Bohr model.

Example Draw the Bohr model for the most abundant isotope of Phosphorus. Z = From Periodic Table Gives #p and #e for neutral atom. Find most abundant isotope mass number, A = on list of abundances. Determine #n. A – Z Draw a nucleus for the neutrons and protons. Label. Draw a circle around the nucleus for K. Place up to 2 electrons on this orbit. Draw a circle around K for L. Place up to 8 electrons on this orbit. Continue with M and/or N with 18, and 32 electrons, until all electrons used.

Quantum Mechanics Why QM needed? Bohr model starts making errors after Z= 18. Same as Bohr model except for how the energy levels are described. Electrons located in orbitals. Mathematical description is a “wave function” – Schrödinger Explains the wave property of matter. Strategy to understand QM: Learn what the orbitals look like and how they’re organized on H atom with activity (today) Populate the orbitals with electrons to describe other atoms using the periodic table (next time)

Shapes of Orbitals Using different shapes is one way QM creates its quantized energy levels. The more complicated the shape, the higher the energy level. Four basic orbital shapes: s spheres, p dumbbells, d 4 leaf clovers, f complicated

Features of Orbitals Orbitals vary in size. Orbitals vary in shape. The bigger an orbital, the higher the energy level Orbitals vary in shape. The more complicated the shape, the higher the energy level. Each orbital can hold up to 2 electrons (0, 1 or 2)

S, P, D, and F Orbitals

Quantum Mechanics Atomic Model - Electrons organized on 4 levels 1) Shells 1, 2, 3, 4, 5, 6, 7 2) Subshells s, p, d, f 3) Orbitals 4) An orbital can hold up to two electrons. S subshells contain 1 orbital (room for 2 e) P subshells contain 3 orbitals (6 e) D subshells contain 5 orbitals (10 e) F subshells contain 7 orbitals (14 e) Shell 1 – s (2e) Shell 2 – s and p (8e) Shell 3 – s and p and d (18e) Shell 4 – s and p and d and f (32e) Shell 5 – s and p and d and f (32e) Shell 6 – s and p and d (18e) Shell 7 – s and p (8e) 2 + 8 + 18 + 32 + 32 + 18 + 8 = 118 Structure for all 118 known elements.

Each small box with a 2 represents a single empty orbital that has a capacity of 2 electrons.

Subscripts (x, y, z, xy, yz etc… Quantum Numbers Four Quantum Numbers used to describe the structure. Memory items. Quantum Number Name Allowed Values Determines Specifies a Common labels n Principle 1, 2, 3, 4….. Size and Energy Shell 1,2,3,4… (Period #) Angular Momentum 0, 1, 2… (only up to n-1) Shape Subshell s, p, d, f ml Magnetic Orientation Orbital Subscripts (x, y, z, xy, yz etc… ms Spin +½ or -½ Electron Up ↑, Down ↓

Exit Slip - Homework Exit Slip: Draw the Bohr Model for Oxygen-16 What’s Due? (Pending assignments to complete.) Bohr Model Worksheet, Atomic Structure Worksheet What’s Next? (How to prepare for the next day) Read Holt p84 - 88