2017 SSNI Atomic Fundamentals Marissa Reigel A discussion and activities about the building blocks of matter.

Matter Term that describes all of the physical substances around us your table your body your pen or pencil Everything!

Matter… Anything that Matter is made up of different kinds of atoms has mass and takes up space (has volume) Matter is made up of different kinds of atoms

Matter… Includes all things that can be Does not include seen tasted smelled touched Does not include heat sound light

Activity: How big is an atom? Materials Sheet of paper Scissors Procedure Cut paper in half Discard half and cut remaining sheet Repeat 90 times

Models Often used for things that are too small to be observed large to be observed difficult to be understood easily

Models… In the case of atoms, scientists use large models to explain something that is very small Models of the atom are used to explain data or facts that were gathered experimentally Models are theories

Early Models of the Atom Empedocles (490 BC) Suggested there were four basic elements Earth Air Fire Water Ratio of elements determined the substance Stone was thought to contain a high amount of earth Animals were thought to have a higher ratio of both water and fire

Early Models of the Atom… Democritus (550 BC) Proposed the universe was made of empty space and tiny bits of stuff called “atomos” Atoms could not be divided Reasoned, “All that exists are atoms and space. Everything else is opinion.”

Early Models of the Atom… John Dalton All elements are composed of indivisible particles (atoms) Atoms of the same element are the same Atoms of different elements are different Compounds consisted of atoms of different elements combined together Element A atom Element B atom Element C atom Compound with elements A, B, & C

Early Models of the Atom… JJ Thomson Plum pudding model Atom is Made of a positively charged material (pudding or soup) With the negatively charged electrons scattered through it

Early Models of the Atom… Ernst Rutherford Mostly empty space Small, positive nucleus Contained protons Negative electrons scattered around the outside

Early Models of the Atom… P E Niles Bohr Electrons move in definite orbits around the nucleus (like planets around the sun) Nucleus (sun) is composed of protons and neutrons Electrons (planets) orbit around the nucleus Neutrons discovered by James Chadwick

Atomic Structure Nucleus Protons Neutrons Electrons Space

Atomic Structure If an atom could be enlarged to the size of a football stadium… The nucleus (protons and neutrons) would be the size of a grape or a marble at midfield Orbiting electrons would be size of salt grains swirling around the upper deck

Atomic Structure – Bohr’s model based on results of Gold Foil Experiment

Atomic Structure – Bohr’s model based on results of Gold Foil Experiment (Zinc Sulphide)

Activity: What’s Inside the Atom? Roll marble Determine the geometric shape underneath

Atomic Structure… Electrons Tiny, very light particles (negligible mass) Have a negative electrical charge (-) Move around the outside of the nucleus

Atomic Structure… Protons Number of protons = atomic number Much larger and heavier than electrons Have a mass of 1 AMU Protons have a positive charge (+) Located in the nucleus of the atom Atoms with same number of protons are the same element Number of protons = atomic number

Atomic Structure… Neutrons Large and heavy like protons Have a mass of 1 AMU Neutrons have no electrical charge Located in the nucleus of the atom Neutralize repulsive force of positive protons Acts as a “glue” that keeps protons in the nucleus Number of protons + number of neutrons = atomic mass

Isotopes Atoms that have Have the same atomic number Have different atomic mass numbers Same number of protons Different number of neutrons

Isotopes…

Atomic Structure Recap

Describing Atoms Atomic Number is the number of protons In a stable atom, the number of protons equals the number of electrons Atomic Mass Number Number of protons and neutrons Atomic Weight Average mass of the naturally occurring isotopes of an element

Pop Quiz! Which atoms are the same element? What is the mass of… Atom A has 65 protons, 65 neutrons, and 65 electrons Atom B has 65 protons, 66 neutrons, and 65 electrons Atom C has 66 protons, 65 neutrons, and 65 electrons Atom D has 65 protons, 65 neutrons, and 66 electrons What is the mass of… Atom A? Atom B? Atom C? Atom D?

Atoms A, B, and D are the same element Pop Quiz Answers Which atoms are the same element? Atom A has 65 protons, 65 neutrons, and 65 electrons Atom B has 65 protons, 66 neutrons, and 65 electrons Atom C has 66 protons, 65 neutrons, and 65 electrons Atom D has 65 protons, 65 neutrons, and 66 electrons Atoms A, B, and D are the same element What is the mass of… Atom A? 130 amu Atom B? 131 amu Atom C? 131 amu Atom D? 130 amu

Periodic Table of the Elements

- + Ions… An atom that carries an electrical charge If a neutral atom gains an electron, the atom becomes negatively charged Because it has more negative charges than positive charges + -

- + Ions… An atom that carries an electrical charge If a neutral atom loses an electron, the atom becomes positively charged Because it has more positive charges than negative charges - +

Ions… Have either The number of protons does not change in an ion More protons than electrons (positive charge) More electrons than protons (negative charge) The number of protons does not change in an ion The number of neutrons does not change in an ion So, both the atomic number and the atomic mass remain the same

Ions… This atom has lost an electron This atom has gained an electron Now it has one more proton than electron One more proton means one more positive charge This makes the total charge of the atom POSITIVE This atom has gained an electron Now it has one less proton than electron One less proton means one less positive charge This makes the total charge of the atom NEGATIVE

Pop Quiz! What is the overall charge of an atom that has 50 protons , 51 neutrons, and 50 electrons? 50 protons , 51 neutrons, and 49 electrons? 50 protons , 51 neutrons, and 51 electrons?

Pop Quiz Answers What is the overall charge of an atom that has 50 protons , 51 neutrons, and 50 electrons? Neutral 50 protons , 51 neutrons, and 49 electrons? +1 50 protons , 51 neutrons, and 51 electrons? -1

Review Matter is comprised of atoms Atoms are comprised of three types of particles Protons Neutrons Electrons Define an element Located in the nucleus Have a positive charge Have a mass of 1 amu Neutrons Located in the nucleus Have no charge Neutralize protons repulsive force Have a mass of 1 amu Electrons Orbit the nucleus Have a negative charge Have a negligible mass Isotopes Same number of protons Different number of neutrons

Final Exam – Fill in the table Complete the table. Which atoms are the same element? Atom Protons Neutrons Electrons Charge Mass A 80 79 B -1 165 C 90 95 D 180 E 100 +2 F -2 200 G 110 112 220

Final Exam Answers Complete the table. Which atoms are the same element? A and B / C and D / E and F Atom Protons Neutrons Electrons Charge Mass A 80 79 +1 160 B 85 81 -1 165 C 90 95 185 D 180 E 100 93 +2 195 F 105 97 -2 200 G 110 112 220