2010-01-20 Chapter 02 Atomic Structure and Bonding

# 2010-01-20 Chapter 02 Atomic Structure and Bonding -...

This preview shows pages 1–7. Sign up to view the full content.

ISSUES TO ADDRESS... What promotes atomic bonding? What types of bonds are there? What properties are inferred from bonding? 1 CHAPTER 2: Atomic Structure & Interatomic Bonding Why study Atomic Structure & Interatomic Bonding? Type of bond allows us to explain a material’s properties. e.g. Metallic bonded materials are good conductors of heat and electricity due to free electrons. Ionically and covalently bonded materials are typically insulative to heat and electricity e.g.ceramics.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
BACKGROUND An Atom is the basic unit of matter. Atom has a Nucleus composed of Protons (positively charged, +) & Neutrons (neutral). Mass proton = Mass neutron = 1.67 x 10 -27 kg Number of protons = Z = Atomic Number, determines the chemical element Number of Neutrons = N, determines the isotope Sum of masses of protons and neutrons = A = Atomic Mass Atomic Weight = Weighted Average of Atomic Masses, in g/mol The Nucleus of an Atom is encircled by moving Electrons (negatively charged, -) Mass = 9.11 x 10 -31 kg <<< protons and neutrons. Charge magnitude for an electron = -1.60 x 10 -19 C Charge magnitude for a proton = +1.60 x 10 -19 C Electrons strongly influence the magnetic properties of atoms. Number of electrons = Number of protons for electrically neutral or, complete atom. 1 mole of matter = 6.023 x 10 23 atoms or molecules = Avogadro’s number
Chapter 2- Nucleus: Z = number of protons 2 orbital electrons: n = principal quantum number n=3 2 1 N = number of neutrons Adapted from Fig. 2.1, Callister 6e. BOHR ATOMIC MODEL In this model, electrons are assumed as particles revolving around nucleus in discrete orbitals.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Wave-mechanical model considers electron to exhibit both wave- like and particle-like characteristics. Position of electron is described by probability distribution Electron in atom is characterized by Quantum Numbers . Shells: principal quantum no.(n = 1,2,3,4,.. or, K, L, M, N) Subshells: second quantum no.(s, p, d, and f) Energy states: third quantum no. Spin moment: fourth quantum no. WAVE-MECHANICAL ATOMIC MODEL Principal Quantum No Shell Subshell No. of Energy State No of Electrons Per Subshell Per Shell 1 K s 1 2 2 2 L s 1 2 8 p 3 6 3 M s 1 2 18 p 3 6 d 5 10 4 N s 1 2 32 p 3 6 d 5 10 f 7 14
Shells s,p,d,f are subshells ELECTRON ENERGY STATES 1. For smaller quantum number energy is lower. 1s < 2s < 3s 2. Within each shell energies are: s < p < d < f 3. There may be overlap in energies in the adjacent shells. e.g. 3d > 4s Electrons tend to occupy lowest available energy state. Important

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Chapter 2- have discrete energy states or, levels. tend to occupy lowest available energy state. 3 Increasing energy n=1 n=2 n=3 n=4 1s 2s 3s 2p 3p 4s 4p 3d Electrons... Adapted from Fig. 2.5, Callister 6e. ELECTRON ENERGY STATES Electron can change energy to higher energy (by absorbing energy) or, lower energy (by emitting energy).
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern