1. Atom 2. Proton 3. Nucleus 4. Neutron 5. Electron 6. Mass number 7. Atomic number 8. Atomic mass unit 9. Isotope 10. Atomic Mass Due Tomorrow! First column: words Second column: definition from text Third column: definition in your own words Fourth column: Picture or example

SC3. Students will use the modern atomic theory to explain characteristics of atoms.

“Atomic Theory and Structure”

OBJECTIVES: OBJECTIVES: Explain Dalton’s atomic theory. Explain Dalton’s atomic theory. Identify the parts of an atom, their location, charge, and relative mass. Identify the parts of an atom, their location, charge, and relative mass. Determine the numbers of subatomic particles in an atom. Determine the numbers of subatomic particles in an atom.

Democritus’s Atomic Philosophy Democritus- all matter is made up of imperishable, indivisible units, which Democritus- all matter is made up of imperishable, indivisible units, which he called atoma. he called atoma.

Dalton’s Atomic Theory 1)All elements are composed of atoms. 2) Atoms of the same element are identical. Atoms of different elements are different. John Dalton (1766 – 1844)

3)Atoms of different elements can combine to form compounds. 4)In chemical reactions, atoms are combined, separated, or rearranged, but never changed into atoms of another element.

Modern Theory One change to Dalton’s atomic theory is that atoms are divisible into subatomic particles: One change to Dalton’s atomic theory is that atoms are divisible into subatomic particles: Electrons Electrons Protons Protons Neutrons Neutrons

The Subatomic Particles LocationCharge Relative mass in amu Function Proton Neutrons Electrons amu amu: mass of 1/12 of a carbon atom

Atom Math Atomic number: number of protons (and electrons IF atom is neutral) Atomic mass: called mass number when rounded to nearest whole number. Mass Number equals protons + neutrons.

Atom Math Protons: atomic number Protons: atomic number Electrons: same as protons if atom is neutral Electrons: same as protons if atom is neutral Neutrons: mass number – atomic number Neutrons: mass number – atomic number protons: ________ neutrons: ________ electrons: ________

Element Atomic Number Number of Protons Number of Electrons Number of Neutrons carbon Phosphorus Gold

Symbol Shorthand X Mass number Atomic number Subscript → Superscript → Carbon Phosphorus Gold

Work Session Subatomic Particle Counting WS—15 minutes Subatomic Particle Counting WS—15 minutes

Atomic Structure Part 2“Isotopes and Ions”

Ions When an atom loses or gains electrons it is called an ion. The number of electrons lost or gained is indicated by a charge. When an atom loses or gains electrons it is called an ion. The number of electrons lost or gained is indicated by a charge. ElementProtonsElectronsIon OxygenGains 2 electrons AluminumLoses 3 electrons BerylliumLoses 2 electrons BromineGains 1 electron

Assignment Ion Practice Set Finish for homework

Ion Review ElementNumber of protons Number of Electrons Ion SulfurGains 2 electrons SodiumLoses 1 electron Boronloses 3 electrons

Atomic Structure Part 2“Isotopes and Ions”

Isotopes Atoms of the same element can have different numbers of neutrons. Thus, different mass numbers.

Naming Isotopes To distinguish between isotopes of the same element, put the mass number after the name of the element: To distinguish between isotopes of the same element, put the mass number after the name of the element: AZAZ ProtonsNeutrons Oxygen-18 Aluminum Be (beryllium-10) 79 Br (bromine-79) Potassium-41 X

Isotopes Elements occur in nature as mixtures of isotopes. So, atoms of the same element aren’t necessarily the same…. AVERAGE atomic mass

Isotope Review ProtonsNeutrons Carbon-12 Carbon-14 Uranium-238 Uranium-235 Hydrogen-1 Hydrogen-2 Hydrogen-3

Work Session Complete Ion Practice Set and Isotope Practice Sets (15 minutes) Complete Ion Practice Set and Isotope Practice Sets (15 minutes)

Atomic Mass  The average atomic mass: is based on the abundance (percentage) of each variety of that element in nature.

Lesson Preview Argon has three naturally occurring isotopes: argon-36, argon-38, and argon-40. Based on argon’s reported atomic mass, which isotope do you think is the most abundant in nature? Poll everywhere response

To calculate the average atomic mass: Multiply the atomic mass of each isotope by it’s abundance percentage (expressed as a decimal), then add the results.

Atomic Masses Isotope Atomic mass % in nature Carbon % Carbon % Carbon-14<0.01% negligible Atomic mass is the average of all the naturally occurring isotopes of that element. Carbon =

Average Atomic Mass Rubidium has two common isotopes, Rb-85 and Rb-87. If the abundance of Rb-85 is 72.2% and the abundance of Rb-87 is 27.8%, what is the average atomic mass of rubidium?

On Your Own Titanium has five common isotopes: 46 Ti (8.0%), 47 Ti (7.8%), 48 Ti (73.4%), 49 Ti (5.5%), 50 Ti (5.3%). What is the average atomic mass of titanium?

Beanium Lab Purpose : To illustrate the relationship between isotopic mass, isotopic abundance, and atomic mass.

Lab Hints Read the instructions! Read the instructions! Everyone participate in counting beans. Everyone participate in counting beans. Do not lose your beans and clean up when you are finished. Do not lose your beans and clean up when you are finished.

 Work on the following assignments: ◦ Beanium Lab ◦ Average Atomic Mass Practice Worksheet