Key Concept 21: The 3 I’s of Chemistry Identity- Protons Isotopes- Neutron Ions- Electron

Identity- Protons Each element contains a unique positive charge in their nucleus. Key Concept 22: The number of protons in the nucleus of an atom identifies the element and is known as the element’s atomic number.

Isotope- Neutrons All neutral atoms of a particular element have the same number of protons and electrons but the number of neutrons in the nucleus can differ. Key Concept 23: Atoms with the same number of protons but different numbers of neutrons are called isotopes. 1913 Fredrick Soddy discovered isotopes. “certain elements exist in two or more forms which have different atomic weights but which are indistinguishable chemically.”

Isotope- Neutrons

There is only one type of carbon atom Misconception There is only one type of carbon atom

Greek Philosophers (cont.) What were the errors in the Dalton’s Atomic Theory?

Mass of Atoms One atomic mass unit (amu) is defined as 1/12th the mass of a carbon-12 atom. One amu is nearly, but not exactly, equal to one proton and one neutron.

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Isotope- Neutrons Isotopes containing more neutrons have a greater mass. Isotopes have the same chemical behavior. Key Concept 24: The mass number is the sum of the protons and neutrons in the nucleus.

Isotope- Neutrons The relative abundance of each isotope is usually constant.

Element (X)- Atomic Mass Isotope- Neutrons Key Concept 25: Isotope Format Atomic Mass X Atomic Number Element (X)- Atomic Mass

What is this atom mass? 11 B 5 11 Boron- 11

Room # 169429 12 C 6 12 What is this atom’s mass?

14 c 8 How many neutrons does this atom have?

? c 6 13 What would this atom’s mass be if it has 7 neutrons?

4 He 2 How many neutrons does this atom have?

Ion- Electron Key Concept 26: An ion is an atom or bonded group of atoms with a positive or negative charge.

Ion- Electron Cation – positively charged ion Anion – negatively charged ion Polyatomic Ions “Poly” = many “atomic” = atoms Ion = charged Polyatomic ion - many atoms bonded together having an overall charge Look at your Periodic Table

How many electron does this ion have? + Li 2

What type of ion is this? +1 Li cation

How many electron does this ion have? +2 Be 2 electrons

4± C

C -4 What type of ion is this? How many electron does this ion have? Anion 10 How many electron does this ion have?

How many electron does this ion have? +2 Ca 18

How many electron does this ion have? - F 10

The Basics The Foundations The Building Blocks of Chemistry Call It Whatever You Want They Are Must Knows

You must be able to: Read a periodic table and use to key to determine: Understand isotope format: lithium-6  verse lithium-7 6Li 7Li Understand how to write ions: Na1+ Fe2+

What is my atomic number? What is my average atomic mass? What is my name? What is my atomic number? What is my average atomic mass? (Pick one of my isotopes on the left side of the card). What is the atomic mass of that particular atom? 5. How many protons do I have (in the isotope)? 6. How many neutrons do I have (in isotope)? 7. How many electrons do I have if I am neutral(in isotope)? (Pick an ion of the right side of the card) How many protons and electrons do I have? 9. (Consider that I am the previous chosen isotope in question 4 and a neutral atom) What happens to me if I gain a p+ (I become _________.) no ( I become _________.) e- ( I become _________.) 10. What happens to me if I lose a I become a new element (nitrogen) I become a new isotope of carbon (carbon-15) I become a new ion (anion) with a charge of -1 (C-1)

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Today Get with your lab partners and complete the 10 questions for becoming an atom with two more cards. Rapid Fire What you need to know Pass out Practice Problems B Note card research

What is my atomic number? What is my average atomic mass? What is my name? What is my atomic number? What is my average atomic mass? (Pick one of my isotopes on the left side of the card). What is the atomic mass of that particular atom? 5. How many protons do I have (in the isotope)? 6. How many neutrons do I have (in isotope)? 7. How many electrons do I have if I am neutral(in isotope)? (Pick an ion of the right side of the card) How many protons and electrons do I have? 9. (Consider that I am the previous chosen isotope in question 4 and a neutral atom) What happens to me if I gain a p+ (I become _________.) no ( I become _________.) e- ( I become _________.) 10. What happens to me if I lose a I become a new element (nitrogen) I become a new isotope of carbon (carbon-15) I become a new ion (anion) with a charge of -1 (C-1)

Rapid Fire 9. What happens to me if I gain a p+ (I become _________.) no ( I become _________.) e- ( I become _________.) 10. What happens to me if I lose a

Happy Atoms Key Concept 27: A happy ATOM is an ATOM that has its orbitals (shell) all full. In order to become full that atom must gain or lose electrons. Most atoms form compounds in order to be happy. Nacl examples Take out periodic tables Reference back to naming Draw bohr models and show electrons transferring Now rapid fire for #9 #10 on white board

What do you need to know?? Determining the number of electrons is the most difficult. You need to be able to answer these type of questions when talking about elements. How many electrons does a neutral atom of Ca have? What is the most common ion Oxygen will form? How many electrons does Br -1 have? First 2 questions all you need is your periodic table -20 -cation O-2 - -35 + -1 = 36 electrons

Practice Problems B

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Mass of Atoms (cont.) Key Concept 27: The average atomic mass of an element is the weighted average mass of the isotopes of that element.

Practice Problems you need a stamp Key Concept 28: The four isotopes of lead and its abundances are: Pb-204, 1.37%; Pb-206, 26.26%; Pb-207, 20.82%; and Pb-208, 51.55%. Calculate lead’s approximate atomic mass.

Practice Problems you need a stamp Key Concept 29: Calculate the estimated average atomic mass of neon if neon exists naturally as 90.92% neon-20, 0.257% neon-21, and 8.82% neon-22.

Calculating Atomic Mass Move into shoulder partners Work through the worksheet together. If you get done before it is time to move on get out practice problems B and complete.

Blank Sheet of Paper… answer these Tell me how many electrons are in these 3 ions K+ P-3 Be+2 List the discovery's and importance of Bohr, Rutherford, Thomson, Dalton Complete the Electron Configuration (long and Nobel Gas) for Al, Se and C What is the average atomic mass and what is the element X-23.985,78.70%; X-24.986 10.13%; 25.983 11.17%

Reminder Reminder Prove it Quiz on Wednesday. Quiz 2 you need to take by Quiz 3 will be available on

Review Draw Bohr model diagrams for the following elements: Fluorine Chlorine Carbon Silicon

For the following elements list the electron configuration. Oxygen Cesium Krypton

For the following elements list the noble-gas notation electron configuration Boron Phosphorus Lead

How many electrons are in each orbital D P F

How do you correctly write an element in isotope format?

How many protons and electrons are in the following Ions Cl- Al+3 Mg+2 O-2

Draw the Lewis dot structure for the following atoms: a. hydrogen b. helium c. boron

Titanium has five common isotopes: 46Ti (8.0%), 47Ti (7.8%), 48Ti (73.4%), 49Ti (5.5%), 50Ti (5.3%). What is the average atomic mass of titanium?

Calculate the average atomic mass of magnesium using the following data for three magnesium isotopes. Isotope mass (u) relative abundance Mg-24 23.985 0.7870 Mg-25 24.986 0.1013 Mg-26 25.983 0.1117