Atomic Theory and the Structure of AtomsCHAPTERS 4 & 5

An overview of the atom..

Atoms are extremely smallAtoms are mostly empty space.

Reactions are the rearrangements of atoms.

Law of Definite Proportions

The same compound always has the same ratios of elements (mass)

Water – 2 hydrogen and 1oxygenCarbon Dioxide-1 carbon and 2oxygen

Law of Multiple Proportions

Atoms of the Same elements can combine in different ratios

Water-H2O Peroxide-H2O2

Carbon Dioxide CO2

Carbon Monoxide CO

Dalton’s Atomic Theory

All matter is composed of extremely small particles called atoms. Atoms of a given element are identical in size, mass, and other

properties. Atoms of different elements differ in size, mass, and other properties.

Atoms cannot be subdivided, created, or destroyed. Atoms of different elements can combine in simple whole number

ratios to form chemical compounds. In chemical reactions, atoms are combined, separated, or

rearranged

Subatomic Particles

Name Location Mass Charge

Protons Nucleus 1amu +1

Neutrons Nucleus 1amu 0

Electrons Orbitals (in electron cloud)

O amu -1

What is the Structure of an Atom?

Elements are different because they have different numbers of protons.

The Atomic Number is the number of protons.

Mass

The mass of an atom is the total number of protons and neutrons. So the mass of an atom is located…

These are sometimes called nucleons

Charge

An atom is neutral, so the number of electrons is the same as the number of protons.

Practice

Element

Name Protons Neutrons

Electrons

C

sulfur

8

35 45

Practice

Element

Name Protons Neutrons

Electrons

C carbon 6 6 6

S sulfur 16 16 16

O oxygen 8 8 8

Br bromine 35 40 35

Isotopes: versions of an element with differing number of neutrons

Because the number of neutrons is different the mass is different and that is how the isotopes are named.

Examples to KNOW:Carbon-12 & carbon-14Hydrogen, deuterium, and tritium

Isotope: Name Atomic

numberMass number

protons neutrons

Carbon-12 12

Carbon-14 14

hydrogen 1

Deuterium 2

Tritium 3

Isotope: Name Atomic

numberMass number

protons neutrons

Carbon-12 6 12 6 6

Carbon-14 6 14 6 8

hydrogen 1 1 1 0

Deuterium 1 2 1 1

Tritium 1 3 1 2

Ions: an atom with a charge

A charge is the result an in balance of protons and electrons. This happens when an atom gains or loses electrons.

A negative charge means more electrons; positive means less electrons.

IONSElement Atomic

NumberProtons Electrons

Cl-1 17 17

H+1 1 1

O-2 8 8

Ca+2 20 20

IONSElement Atomic

NumberProtons Electrons

Cl-1 17 17 18

H+1 1 1 0

O-2 8 8 10

Ca+2 20 20 18

Do Now

1. If you score 33 out of 40 questions, what percentage did you get correct?

2. If you got 85 % correct on a test of 25 questions, how many did you miss?

3. If you got 92% MP1, 80% on the midterm, and 90% on MP2, and 75% on the final, what was your final grade?(each marking period is 40% and each test 10%)

Mass Number

The mass number of an atom, ion or isotope is the total number of nucleons.

Carbon-14; 14C; mass = 14amuCarbon; carbon-12; 12C; mass = 12 amuSo how could you write

DueteriumTritium

Average Atomic Mass(atomic mass)The weighted average of the

isotopes found in a natural sample. for each isotope multiple mass by decimal form of %abundance

Find the sum.

Example 1:

Sample Problem

Copy one of the Many examples !

MODELS

Models are constructs to explain ideas and theories.

As _____ are gather the models have been improved

Bohr model Based on spectra data.Electrons were found in orbitals. Electrons can absorb energy and move to higher orbitals-___________ state.

The ________ state is the lowest energy level.

Orbitals/Energy levels/shellsEnergy Level # electrons1 22 83 84 185 18

Skill: You should be able to draw a Bohr diagram for elements 1-20

Draw a Bohr model for:

OxygenPhosphorus

Limits of Bohr model

Only really worked for hydrogen.Uncertainty principal- regions of space where likely to find them- electrons repulsion.

Spin- balances by only 2/shell

The Electron Cloud

LEQ: How electron arranged in the electron cloud?

Game Rules

1. A full circle has exactly each color. 2. Fill from the bottom to the top.3. Fill across row with one color and then

go back to fill with the other.

TOD

3 things you learned about quantum model

2 ways bohr and quantum are the same1 question you need answered

Quantum Numbers

Quantum Number What does it mean

Principal quantum Number (n)

Describes the size of the energy level

Angular Quantum number (l)

Describes the shape of the orbital (S<PD<F)

Magnetic Quantum Number (m)

Describes the orientation of the orbital

Spin Quantum Number (s)

Describes if the electron is spinning clockwise or counter clockwise

Level Orbitals

Sub-orbitals

Number of orbitals

#Electrons

1 s 1 1 2

2 Sp

13

4 26 =8

3 SPD

135

9 2610 =18

4 SPDg

1357

16 2610 =3214

SKILL: Put an example of each.

Orbital Diagram Electron Configuration Notation (spdf) Lewis Dot Diagrams

Location on Periodic Table indicated orbital being filled.

The Rules

Aufbau Principal: Electrons fill orbitals from the lowest level and and move upward. (Analogy: Fill the bus from the back to the front)

Hund's Rule: In orbitals with sublevels, one electron fills each sublevel before a second electrons shares the orbital. Also each of the first electrons have the same spin. (Analogy: Each seat on bus gets one person before sharing a seat.)

Pauli Exclusion Principal: No two electrons that share an orbital have the same spin. (Each seat has one boy and one girl.)