 Write about what you know of the following people:  John Dalton  J. J. Thomson  Ernest Rutherford

Key Learning: The number, type and arrangement of subatomic particles differs with each element.

Concept

CHOOSE 1: HOW TO DO VOCABULARY:  Write word and definition. Underline and highlight vocabulary word.  Write word on front and definition on back of index cards.  Create a poem or rap of vocabulary words and definitions.  Create foldable with words and definitions. VOCABULARY  Subatomic particles  Orbits  Nucleus  Atom***  Electron cloud  Ground state  Excited state  Absorption  emission

John Dalton (1766–1844)

 Dalton’s Atomic Theory  First to propose that elements were comprised of atoms  Write 5 parts to Dalton’s Atomic Theory pg. 68

 Modern Atomic Theory  ***modification of Dalton’s Atomic Theory***  1. All Matter is composed of atoms  2. Atoms of any one element differ in properties from atoms of another element How is this different than Dalton’s Theory?  there is no mention of an atom being smallest particle

Investigated cathode rays.

 J.J. Thomson  Discovered electrons ~1897 by using cathode ray tubes  “plum-pudding” model  Thought the atom was solid

Cathode (-) Anode (+) Electric plates (one +, one -) partially evacuated glass tube that produces a beam between the cathode and anode

Discovered: Alpha particles and Beta particles

 Ernest Rutherford  Credited with the development of the nuclear model for the atom  Used gold foil method. This disproved Thomson’s model.  3 postulates  Most of atom’s mass and all of its positive charge are in a localized small core---nuclear theory  Most of atom’s volume is empty space in which tiny, negatively charged electrons are dispersed  Since electrons are electrically neutral, there are as many (+) particles (protons) with the nucleus as there are (-) electrons outside the nucleus – or – protons = electrons

 10/08/2012  Write Question and Answer  What did Rutherford do that disproved Thomson’s model?

 Developing a New Atomic Model  EM Spectrum Diagram  Energy moves as a wave  Includes all electromagnetic radiation  Visible light is only a small part of the EM spectrum ( nm)

 EM radiation  1.Properties of Light  a. visible light  Form of energy traveling in waves  b. speed of light (c)  Wavelength X frequency  The shorter the wavelength, the greater the frequency

c. Characteristics of Waves  Wavelength  Distance from peak to peak of a wave  Measured in nm  Frequency  Number of waves that pass through a set point in a given amount of time (waves/sec)

 Photoelectric effect  Emissions of electrons from metals that have absorbed photons  Photon  A particle of EM radiation that has a zero mass and a quantum amount of energy  Quantum  Minimum amount of energy that can be gained or lost by an atom

 Bohr model  Lowest energy state of an atom  ground state  An atom having a higher potential energy  excited state  Energy must be absorbed to move electrons to a higher orbit (ground state  excited state)  Energy is emitted (given off as EM radiation) when electrons are moved to a lower orbit (excited state  ground state)

When an element is heated up, it gives off light of specific colors: emission spectrum When light goes through an element, it absorbs light of specific colors: absorption spectrum

 Bohr model continued…  Electrons circle nucleus in orbits (energy levels)  When electrons are in orbit, its energy is fixed  Lowest energy levels are closest to the nucleus while Highest energy levels are farther away from nucleus  Electrons can move to higher energy levels when hit by a photon

 Structure of the atom  3 subatomic particles identify the element  1. protons  Ernest Rutherford (1909)  (+) charge  Mass X 10 - ² 7 g – or – 1 amu  Relative mass  Held by nuclear forces

 2. Neutron (N)  James Chadwick (1932)  No charge; neutral  Has mass of X g – or – 1 amu  Relative mass =  In nucleus and held by nuclear forces  Responsible for isotopes- atoms of same element with different #’s of neutrons

 3. Electron (e-)  J.J. Thomson (1897)  ( – ) charge  Negligible mass (1/1836 amu –or X g  Relative mass  In orbitals within the electron cloud  Makes volume of atom  # in last energy level determines the chemical activity

 Things to Note :  Mass of atom is in the nucleus  Atomic radius (Angstrom) is distance from nucleus to outer edge of electron cloud  Volume of atom is from electron cloud

Concept

 Write word and definition. Underline and highlight vocabulary word.  Write word on front and definition on back of index cards.  Create a poem or rap of vocabulary words and definitions.  Create foldable with words and definitions.  Atomic number  Average atomic mass  Isotopes  Protons  Neutrons  Electrons  Mass number

 Write question and answer.  Write the correct nuclear symbol for the following:  An atom has 23 protons and 29 neutrons.  An atom has 42 protons and 49 neutrons.

 You can use information from periodic table to determine the structure of an atom  Atomic number (identifies the element)  Atomic symbol  Element name  Average atomic mass  round to nearest whole number to get the mass # (total number of protons and neutrons that make up nucleus of an isotope.

 Where does average atomic mass come from?  Average of atomic masses of naturally occurring isotopes of that element  Example: We have a box of 2 types of marbles (100 total). If 25% of these marbles have a mass of 2 g and 75% have a mass of 3 g, then what is the average mass of the marbles?

 APPLY to elements!!!  We have 69.15% of Cu-63, with an atomic mass of amu and 30.85% of Cu-65 with an atomic mass of What is the average atomic mass?

 You APPLY to elements!!!  There is % of O-16 with an atomic mass of amu and.038% of O-17 with an atomic mass of amu and 0.205% of O-18 with an atomic mass of amu. Calculate the average atomic mass.

 Isotopes  They have the same number of protons and electrons as a neutral element; but, different number of neutrons (therefore different masses).  Even though this affects average atomic mass –or- mass number, is does not significantly alter their chemical behavior

 Nuclear Symbol  Superscript indicates the mass number (p+n)  Subscript indicates the atomic number (p)  Hyphen Notation  Element symbol, hyphen, mass number

 Mathematical Equations  Atomic number = # of p (also tells you # of e)  Mass number = # of p + # of N  Number of Neutrons = mass # - atomic #

 Complete worksheet 2 and 3

Concept

CHOOSE 1: HOW TO DO VOCABULARY:  Write word and definition. Underline and highlight vocabulary word.  Write word on front and definition on back of index cards.  Create a poem or rap of vocabulary words and definitions.  Create foldable with words and definitions. VOCABULARY  Quantum numbers

 With the Bohr model, we can show what energy level the electrons are in. However, the Bohr model does not show where the electron is exactly located or what orbital they are in.

 Where are electrons located in an atom?  Electron cloud  Electrons are located in specific locations within energy levels. These levels are known as orbital “home”  Atomic orbitals vary in amount of energy, shape and location outside of nucleus

 Quantum numbers are used to describe the atomic orbitals and the electrons which occupy them  “address” of an electron  Quantum Theory-describe proportion of electrons mathematically

 4 Quantum Numbers  Principle Quantum Number (n)  Energy level of orbital  7 energy levels (7 periods of table)  Angular Momentum Quantum Number (l)  Indicates the shape of the orbital

 Magnetic Quantum Number (m)  Indicates the orientation of the orbital  Spin Quantum Number (+ ½ or – ½ )  Electrons are constantly spinning (clockwise/counter-clockwise)

Concept

CHOOSE 1: HOW TO DO VOCABULARY:  Write word and definition. Underline and highlight vocabulary word.  Write word on front and definition on back of index cards.  Create a poem or rap of vocabulary words and definitions.  Create foldable with words and definitions. VOCABULARY  Orbital notation  Electron configuration notation  Noble gas notation  Hund’s Rule  Aufbau’s Principle  Pauli Exclusion Principle  Heisenberg Uncertainty Principle

 Pauli Exclusion Principle  No two electrons can have the same 4 quantum numbers  Atomic orbitals  Electrons are not only located in energy levels; but, they are more specifically located in orbitals

 4 types of Atomic Orbitals  s, p, d, and f

 S-orbital  Shaped like a sphere  1 per energy level  Can hold 2 electrons  S-block is groups 1-2

 P orbital  Shaped like a dumbbell  3 per energy level  One on x-axis, y-axis, and z-axis  Each one holds 2 electrons for a total of 6 electrons  Groups 13-18

 D-orbital  Begins at energy level 3  5 different orbitals  Each hold 2 electrons for a total of 10 electrons  Groups 3-12

 F-orbital  Begins at 4 th energy level  7 different orbitals  Each has 2 electrons for a total of 14 electrons

 Be looking over notes from board and yesterday’s powerpoint

 Aufbau Principle  Electrons fill the atomic orbitals in a very specific way; based on energy  An electron will occupy the lowest energy orbitals first  Follow the arrows to fill atomic orbital

 Hund’s Rule  Orbitals of equal energy are filled by one electron before a second electron is added

 Using orbital notation (combining Aufbau and Hund’s)  Use dashes to represent orbitals and arrows to represent electrons  1. Use atomic number to know how many electrons are present  2. Fill in orbitals based on Aufbau’s chart and Hund’s Rule

 10/18/2012  Write the orbital configuration for:  Sodium  Magnesium

 Electron Configuration Notation  Instead of using dashes and arrows, use coefficients and superscripts  1. use atomic number to know how many electrons are present  2. exponents show number of electrons in each orbital  3. coefficients represent energy level

 Noble Gas Notation  Use noble gases to make notation shorter  Noble gas  has a full s and p orbital  octet  To read: Add the electrons to the atomic number of the noble gas

 Valence Electrons  Electrons located in the last energy level  Determines the chemical properties of that element