CHEMISTRY UNIT CHAPTER 3 Atomic Structure Timeline of

CHEMISTRY UNIT: CHAPTER 3 Atomic Structure

Timeline of the Atomic Structure

What is the current structure of an atom?

What is the current structure of an atom? • Protons • Positive (+) Charge • Located in the nucleus • Do not change in numbers

What is the current structure of an atom? • Neutrons • Neutral (0) Charge • Located in the nucleus • Able to change numbers

What is the current structure of an atom? • Electrons • Negative (-) Charge • Located in the electron cloud • Able to change numbers

What is the current structure of an atom? • **Number of Protons and Electrons equal each other** • In a Neutral Atom • Example:

Atomic number • It is the number of protons • Every element has a unique atomic number. • Ex. • Carbon / atomic number = 6 / number of 6 protons = ______ • Nitrogen / atomic number = 7 / number of 7 protons = ______ • Oxygen / atomic number = 8 / number of 8 protons = ______

Atomic mass • It is the mass of an atom • Atomic mass = # protons + # neutrons Atomic Mass - ______ Atomic Number • # neutrons = ______ • Ex. • Carbon has an atomic mass of 12 and an atomic number of 6 12 - _____ 6 = # neutrons = ____ 6 • _____

Atomic mass • It is the mass of an atom • Atomic mass = # protons + # neutrons Atomic Mass - ______ Atomic Number • # neutrons = ______ • Ex. • Bromine has an atomic mass of 80 and an atomic number of 35 80 - _____ 35 = # neutrons = ____ 45 • _____

Reading Atomic Number and Atomic Mass on the Periodic Table

Isotopes • The number of neutrons for an element can vary • Atoms with the same # or protons but different # of neutrons are called isotopes • They are identified by their atomic mass • Ex. 6 6 • Carbon 12: _____ protons and _____ neutrons 7 6 • Carbon 13: _____ protons and _____ neutrons • Carbon 14: _____ protons and _____ neutrons 6 8