Matter Quiz Atomic Theory Notes

Common Core connection Objectives Today I will be able to: Demonstrate knowledge of matter and energy by taking a quiz Identify the parts of the atom and their isotopes Informal Assessment – monitoring student interactions and questions as they complete the practice and quiz Formal assessment – analyzing student responses to the quiz and the practice Common Core connection Build Strong Content Knowledge Reason abstractly and quantitatively

Lesson Sequence Evaluate: Warm – Up Evaluate: Matter Quiz Explain: Atomic Theory Notes Elaborate: Atomic Theory Practice Evaluate: Exit Ticket

Warm - Up What are some pieces of evidence for a chemical change? What is the difference between a physical change and a chemical change? What is the difference between homogeneous and heterogeneous mixtures?

Objective Today I will be able to: Demonstrate knowledge of matter and energy by taking a quiz Identify the parts of the atom and their isotopes

Homework Finish Practice Worksheet

Agenda Warm – Up Matter Quiz Atomic Theory Notes Atomic Theory Practice Exit Ticket

What information can we get from the periodic table?

Atomic Number number of protons in the nucleus You cannot change the number of protons!!! Determines the identity of an element Also the number of electrons in a neutral atom

Atomic Number What is the atomic number of carbon? 6 How many protons and electrons would there be in a neutral atom of carbon? 6 protons and 6 neutrons How many protons and neutrons would there be in a neutral atom of oxygen? 8 protons and 8 neutrons

Atomic Mass Measured in atomic mass units The number or protons and neutrons in an atom

How did we arrive at measuring atomic mass in atomic mass units? Based on the Carbon-12 scale By international agreement, a carbon atom contains 6 protons and 6 neutrons, or 12 amu Therefore, 1 amu is 1/12 of a carbon atom Since the mass in grams of protons and neutrons are about the same, they both have an atomic mass unit of 1

Why aren’t electrons accounted for in the calculation of the atomic mass? Electrons are small! It takes almost 2,000 electrons to equal the mass of one proton or neutron Electrons are assumed to have a mass of 0 amu

If each proton and neutron has a mass of one amu, then why aren’t the atomic masses on the periodic table whole numbers? Isotopes of elements atoms with the same number of protons but different numbers of neutrons

Ions When an atom gains or loses an electron, an Ion is formed Cation – atom loses an electron and makes a positive ion Example: Lithium (Li) loses one electron It becomes Li+ Anion – atom gains an e- and makes a negative ion Example: Sulfer (S) gains two electrons It becomes S-2

Ions Examples What is the chemical symbol for the ion with: 13 protons and 10 electrons - Al+3 7 protons and 10 electrons - N-3

How many protons and electrons are present in a(n): S-2 ion - 16 p+ and 18 e- Li+1 ion - 3 p+ and 2 e-

Be careful with terminology! Atomic Mass – average mass of the naturally occurring isotopes of an element Seen on the periodic table Mass Number – number of protons and neutrons in an atom’s nucleus Seen in symbolic representations

Symbolic Representations of Elements An atom with 7 protons and 7 neutrons has a mass number of 14 and is usually written as… N 14 7

Al+3 Se-2 Exit Ticket How many protons, neutrons, and electrons? 27 Al+3 13 13 p+, 14 n, and 10 e- 79 Se-2 34 34 p+, 45 n, and 36 e-