How We Know What We Can’t See Looks Like Day 2 Atom’s Story How We Know What We Can’t See Looks Like Day 2

A. Tom on a Band

Name Symbol Mass Protons p 1 Neutrons n 1 Electrons e-- 1/2000 Two atoms were walking down the road. One turns to the other and says, “I think I’ve lost an electron.” “Are you sure?” asks his companion. “I’m positive”, he replied. Name Symbol Mass Protons p 1 Neutrons n 1 Electrons e-- 1/2000 (actually 1/1840)

Atomic Particles Particle Charge Mass # Location Electron -1 Electron cloud Proton +1 1 Nucleus Neutron

The Atomic Scale Most of the mass of the atom is in the nucleus (protons and neutrons) Electrons are found outside of the nucleus (the electron cloud) Most of the volume of the atom is empty space “q” is a particle called a “quark”

About Quarks… Protons and neutrons are NOT fundamental particles. Protons are made of two “up” quarks and one “down” quark. Neutrons are made of one “up” quark and two “down” quarks. Quarks are held together by “gluons”

Atomic Number (Z) identifies the number of protons identifies the element. Element # of protons Atomic # (Z) Carbon Phosphorus Gold 6 6 15 15 79 79

Mass Number Nuclide p+ n0 e- Mass # the number of protons and neutrons NOT the same as average atomic mass NOT on the PT Mass of the nucleus of an isotope. Written with name in hyphen notation ex. Carbon – 12 Mass # = p+ + n0 Nuclide p+ n0 e- Mass # Oxygen - 10 - 33 42 - 31 15 18 8 8 18 Arsenic 75 33 75 Phosphorus 16 15 31

Nuclear Symbols Mass number (p+ + no) Element symbol Charge (p+ - e-) 2+ Charge (p+ - e-) Atomic number (number of p+)

Isotopes atoms of the same element having different masses varying numbers of neutrons. Isotope Protons Electrons Neutrons Nucleus Hydrogen–1 (protium) 1 Hydrogen-2 (deuterium) Hydrogen-3 (tritium) 2

Composition of the nucleus Atomic Masses Atomic mass is the average of all the naturally isotopes of that element. Carbon = 12.011 Isotope Symbol Composition of the nucleus % in nature Carbon-12 12C 6 protons 6 neutrons 98.89% Carbon-13 13C 7 neutrons 1.11% Carbon-14 14C 8 neutrons <0.01%

But now we know. . . Let’s learn about ISOTOPES! Can you say: PROTON? NEUTRON? ELECTRON? QUARK? But now we know. . . 1. Matter is made of very small particles called “atoms” 2. Atoms cannot be divided, created, or destroyed. Atoms of one kind of element are identical to other atoms of that same element. Atoms of different elements are unlike. Let’s learn about ISOTOPES! 4. Atoms somehow combine in small, whole-number ratios to form chemical compounds. In chemical reactions, atoms are somehow combined, separated, or rearranged.

Isotopes of Hydrogen Protium H Deuterium H Tritium H 1 Protium H 2 3 Deuterium H Tritium H 1 1 1 Deuterium and tritium reveal on click 1 proton 1 neutron Mass = 2 1 proton 2 neutron Mass = 3 1 proton Mass = 1

Relative masses on the P. Table are weighted averages of the isotopes. Atoms of the same element (they have the same number of protons) that have different masses because they have different numbers of neutrons. C C 13 C 14 C 11 12 Carbon – 12 makes up the greatest % of carbon in the universe MASS # 12 C 6 ATOMIC # Relative masses on the P. Table are weighted averages of the isotopes.

Subatomic Particles 3 main subatomic particles Nucleus Proton Neutron Electron Nucleus Center of atom 100 000 times smaller than atom 99.9% of atom’s mass Contains 2 subatomic particles Protons neutrons

Parts of the atom 24 28 22 Ion +2 32S2- 32.07 16 32 16 16 18 Ion 56 Name Symbol Atomic Mass Number Mass number # of protons # of neutrons # of electrons ion/ isotope Charge 11B 10.81 5 11 6 52Cr+2 52.00 52 24 Sulfur – 32 -2 100Ru 101.1 44 4 Titanium-44 47.87 22 +2 32Si 40Ca 40.08 Neither Ytterbium-140 70 Neither Boron – 11   Chromium-52 24 28 22 Ion +2 32S2- 32.07 16 32 16 16 18 Ion 56 Ruthenium-100 100 Isotope 44Ti2+ 22 20 Ion/ isotope 14 18 14 Isotope Silicon-32 28.09 14 32 Calcium-40 20 40 20 20 20 140Yb 173.0 140 Isotope