SC Standards Covered • Standard PS-2.1 Compare the subatomic particles (protons, neutrons, electrons) of an atom with regard to mass, location, and charge, and explain how these particles affect the properties of an atom (including identity, mass, volume, and reactivity). • Standard PS-2.4 Use the atomic number and the mass number to calculate the number of protons, neutrons, and/or electrons for a given isotope of an element.
Scientific Shorthand • Each element can be represented by a one, two, or three letter chemical symbol • Each symbol consists of one capital letter plus one or two lower case letters
Atomic Components Atom - smallest particle of an element which retains the properties of that element.
Atomic Theory • Atoms are building blocks of elements • Similar atoms in each element • Different from atoms of other elements • Two or more different atoms bond in simple ratios to form compounds
Basic Structure • The center of the atom is called the nucleus. • Surrounding the nucleus is the electron cloud.
Subatomic Particles Particle Symbol Location Charge Mass Electron Space around the nucleus 1/1840 amu e-1 -1 In the nucleus Proton p+1 +1 1 amu In the nucleus 0 1 amu Neutron n0
Quarks • Quarks – particles that make up protons and neutrons • Three quarks make up a proton or neutron
Fine Points to the Structure of the Atom • All of the mass of an atom is located in the nucleus • All of the volume of the atom is taken up by the electron cloud
Atomic Number Atomic number – counts the number of protons in an atom - Used to identify the element - Periodic Table arranged by it Atoms are electrically neutral (not charged) # of protons = # of electrons
Learning Check State the number of protons for atoms of each of the following: A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protons B. Sulfur 1) 32 protons 2) 16 protons 3) 6 protons C. Barium 1) 137 protons 2) 81 protons 3) 56 protons
Solution State the number of protons for atoms of each of the following: A. Nitrogen 2) 7 protons B. Sulfur 2) 16 protons C. Barium 3) 56 protons
Mass Number Mass Number – Counts the number of protons and neutrons in an atom Number of Neutrons = Mass Number – Proton Number (atomic #)
Isotopes Isotopes - atoms of the same element with different numbers of neutrons
Notation of Isotopes Potassium - 40 Mass number 40 K 19 Atomic number
Learning Check Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C 14C 6 6 6 #P _______ _______ _______ #N _______ _______ _______ #E _______ _______ _______
Carbon - 12 Carbon - 13 Carbon - 14
Atomic mass - weighted average of all the isotopes of a particular element • This is the mass indicated on the periodic table. • This number will be closest to the most common isotope of the element.
Learning Check An atom of zinc has a mass number of 65. A. Number of protons in the zinc atom 1) 30 2) 35 3) 65 B. Number of neutrons in the zinc atom 1) 30 2) 35 3) 65 C. What is the mass number of a zinc isotope with 37 neutrons? 1) 37 2) 65 3) 67
Solution An atom of zinc has a mass number of 65. A. Number of protons in the zinc atom 1) 30 B. Number of neutrons in the zinc atom 2) 35 C. What is the mass number of a zinc isotope with 37 neutrons? 3) 67
Learning Check Write the isotope (nuclear) notation for atoms with the following: A. 8 p+, 8 n, 8 e- ___________ B. 17p+, 20n, 17e- ___________ C. 47p+, 60 n, 47 e- ___________
Solution 16O A. 8 p+, 8 n, 8 e- 8 B. 17p+, 20n, 17e- 37Cl 17 C. 47p+, 60 n, 47 e- 107Ag 47