Subatomic Particles (Sections 4.2 and 4.3) Dr. Walker Surry County High School

What will you learn? The subatomic particles located within an atom The location, charge, and relative mass of subatomic particles within an atom How the number of subatomic particles affect the atomic number and mass number of an element To determine atomic symbols from numbers of subatomic particles

Three Subatomic Particles Proton Positively Charged Located in nucleus Larger than electrons, same size as neutron Held in nucleus by nuclear force (aka strong force) Overcomes repulsion of like charged particles

Three Subatomic Particles Neutron No charge Located in nucleus Same size as proton, larger than electrons

Three Subatomic Particles Electron Negatively charged Located in electron clouds (shells) Less massive than protons

Compare and Contrast Chart Subatomic Particle Mass Location Charge Proton 1.67 x 10-27 kg Nucleus + Neutron uncharged Electron 9.1 x 10-31 kg (much smaller) Orbitals (outside nucleus) -

Sub-Subatomic Particles Quarks Located in the nucleus Six “flavors” Protons and neutrons made of quarks and have a different composition New SOL content

Atomic Number Atomic numbers are included in the periodic table For a neutral atom: atomic number = # of protons = # of electrons

Periodic Table Entry

Mass Number Mass number = protons + neutrons Electrons are too small to count (1/1000 the size of protons and neutrons) Mass number is a whole number (not the same as atomic mass)

Average Atomic Mass The average atomic mass for each element is the weighted average of that element’s naturally occurring isotopes Isotope = same # protons, different # of neutrons Protons must stay the same, neutrons can change Mass numbers are whole numbers (can’t have part of a proton or neutron) Atomic masses are decimals because they are averages!!

Learning Check What is the mass number of an element with 7 protons, 8 neutrons, and 7 electrons? What is the atomic number of this element?

Learning Check What is the mass number of an element with 7 protons, 8 neutrons, and 7 electrons? 15 (7 protons + 8 neutrons) What is the atomic number of this element? 7

Relating New Terms Protons Electrons Neutrons ______ Located in _______ Located in ______

Relating New Terms Protons Electrons Neutrons Located in nucleus Mass number Located in nucleus Atomic number Located in orbitals (aka shells)

Element Number of Protons Number of Neutrons Number of Electrons Mass Number lithium 7 carbon chlorine 35 silver 61 lead 207 calcium 20 tantalum 181 radium 226 samarium 88 uranium 238 americium 148 lawrencium 268

Element Number of Protons Number of Neutrons Number of Electrons Mass Number lithium 3 4 7 carbon 6 13 chlorine 17 18 35 silver 47 61 108 lead 82 125 207 calcium 20 40 tantalum 73 181 radium 88 138 226 samarium 62 150 uranium 92 146 238 americium 95 148 243 lawrencium 103 165 268

Atomic Symbols 12 6 C 13 14 Top Number = mass number (protons + neutrons) Bottom Number = atomic number (protons, electrons)

Atomic Symbols 12 6 C 13 14 Protons 6 Neutrons 7 8 Electrons To get neutrons, subtract the bottom number (protons) from the top (protons + neutrons)

Atomic Symbol Practice Give the number of protons, neutrons, and electrons for the following symbols 3517Cl 8537Rb 7935Br

Atomic Symbol Practice Give the number of protons, neutrons, and electrons for the following symbols 3517Cl 8537Rb 7935Br 17 protons 17 electrons 18 neutrons 37 protons 37 electrons 48 neutrons 35 protons 35 electrons 44 neutrons

Atomic Symbol Practice Give the atomic symbol for: An atom with 3 protons, 3 electrons, and 4 neutrons An atom with 15 protons, 15 electrons, and 17 neutrons

Atomic Symbol Practice Give the atomic symbol for: An atom with 3 protons, 3 electrons, and 4 neutrons 73Li An atom with 15 protons, 15 electrons, and 17 neutrons 3215P

More Practice 8 39 8035Br 45 30 65 Element Atomic Symbol Atomic Number Mass Number # of protons # of neutron # of electron 8 Potassium 39 8035Br 45 30 65

More Practice Oxygen 168O 8 16 3919K 19 39 20 Bromine 8035Br 35 80 45 Element Symbol Atomic Number Mass Number # of protons # of neutron # of electron Oxygen 168O 8 16 Potassium 3919K 19 39 20 Bromine 8035Br 35 80 45 Zinc 6530Zn 30

Isotopes Same atom, different number of neutrons All atoms of an element must have the same number of protons All hydrogens have 1 proton All heliums have 2 protons, etc., etc. The neutrons can be different 11H, 21H, 31H These are called isotopes

Average Atomic Mass The weighted average of all isotopes of an element Average: Add up terms, divide by number of terms Weighted average: Multiply each term by percentage as decimal, add terms No division in a weighted average! Represented by decimal number with each element of the periodic table

Average Atomic Mass Example with grades Johnny has a 90 homework average (20%), 70 quiz average (20%), 60 test average (40%), 60 exam (20%)

Average Atomic Mass Example with grades Johnny has a 90 homework average (20%), 70 quiz average (20%), 60 test average (40%), 60 exam (20%) Regular average (90 + 70 + 60 + 60)/4 = 280/4 = 70 - C Weighted average (90 x 0.2) + (70 x 0.2) + (60 x 0.4) + (60 x 0.2) = 68 - D homework quiz test exam

Average Atomic Mass Chemical example For the element boron, 10B occurs 19% of the time, while 11B occurs 81% of the time.

Average Atomic Mass Chemical example For the element boron, 10B occurs 19% of the time, while 11B occurs 81% of the time. Use the mass number and percentages (as decimals) (10 x 0.19) + (11 x 0.81) = 10.81

Review What is the charge of each subatomic particle? The mass number contains which subatomic particles? The atomic number is equal to which subatomic particles? If a fluorine atom has a mass number of 19, how many protons, electrons, and neutrons does it contain? Give the atomic symbol for an element containing 33 protons, 33 electrons, and 42 neutrons.

Terms To Know Skills To Master Proton Neutron Electron Quark Isotope Mass Number Atomic Number Average Atomic Mass Calculating mass number from numbers of protons and neutrons Calculating protons, neutrons, and electrons from mass number Recognizing isotopes of the same element

Corresponding Text Subatomic Particles – pp. 105-118