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The Nature of Matter! Unit 2: Biochemistry – ATOMS! No Bellringer Today!

The Basics Matter: anything that has mass and takes up space. Atom: The basic unit of matter Element: A pure substance that consists of entirely one atom. Compound: a substance formed by the chemical combination of two or more elements.

Subatomic particles Proton: (+) Positively charged particle in the nucleus of the atom. Neutron: (0) A particle in the nucleus that has no charge. Electron: (-) negatively charged particle that is in constant motion outside the nucleus (in the electron shell).

Sub-Atomic ParticleMassCharge Proton1+1 Neutron10 Electron0 Sub-Atomic Math

The Atom Helium 2 He Helium 4 Atomic Number Element Symbol Element Name Atomic Mass

Mendeleev Each element is made of atoms. The elements are currently arranged by atomic number. I spent my time arranging the elements and came up with the Periodic Table of Elements in 1865.

You can determine the number of protons, neutrons, and electrons using the Periodic table. = number of protons + number of neutrons = number of protons = number of electrons 6 C Carbon 12 Atomic Number Element Symbol Element Name Atomic Mass

The Atom Helium Helium has two protons, two electrons, two neutrons Electrons= Neutrons= 2 He Helium 4 Atomic Number Element Symbol Element Name Atomic Mass Let’s Try It! = 2

Nucleus : Contains Protons and Neutrons Shell contains Electrons The Atom Helium He P:2 N:2 e e

Energy Levels: in electron cloud 1 st Energy Level = Max. of 2 electrons 2 nd Energy Level = Max. of 8 electrons 3 rd Energy Level = Max. of 8 electrons 4 th Energy Level = Max. of 18 electrons Nucleus Electron in 1 st energy level Electron in 2 nd energy level Electron in 3 rd energy level Electron Shell : Energy Levels

Valence Electrons Valence electrons: electrons in the outer most energy level = valence electrons- 8 red dots in outer energy level

Niels Bohr P:5 N:6 B e e e e e Bohr Model

Drawing an atom model… -Begin with the element and determine how many protons, neutrons, and electrons there are. Boron : Atomic Number 5 Atomic Mass 11 Protons: 5 Neutrons: 6 Electrons: 5 go inside nucleus go in electron shell P:5 N:6 B

The Nucleus contains 5 protons and 6 neutrons There are two electrons on the first energy level. This energy level is full, so we go to the next energy level After placing 2 electrons on the first energy level, Boron still has 3 more electrons. These electrons are put on the 2 nd energy level. Valence Electrons: There are 3 valence electrons. To determine this, we look at the outer most energy level (in this case the 2 nd level). Then we count the number of electrons. There are 3 electrons on the 2 nd energy level. P:5 N:6 B Boron

REMEMBER… ALWAYS FILL THE INNER ENERGY LEVELS FIRST!!! START WITH THE 1 ST ENERGY LEVEL!

Draw an atom of… Sodium: Na Atomic #: 11 Atomic Mass: 23 Determine… Protons ( + ) = Neutrons ( 0 ) = Electrons ( - ) = Valence Electrons? = P:11 N:12 Na

Draw an atom of… Beryllium: Be Atomic #: 4 Atomic Mass: 9 Determine… Protons ( + ) = Neutrons ( 0 ) = Electrons ( - ) = Valence Electrons? = P:4 N:5 Be

Draw an atom of… Neon: Ne Atomic #: 10 Atomic Mass: 20 Determine… Protons ( + ) = Neutrons ( 0 ) = Electrons ( - ) = Valence Electrons? = 10 8 NEON IS A STABLE ELEMENT (OR UNREACTIVE) BECAUSE IT’S OUTER ENERGY LEVEL IS FULL!!! P:10 N:10 Ne

Bell Ringer: Please pull out your Periodic Table Lets looks at the element: Chlorine 1.What is it’s Element Symbol? 2.What is it’s Atomic #? 3.How many Protons? 4.How many Neutrons? 5.How many Electrons? 6.Draw a Bohr model of Chlorine 7.How many electrons are in the valence shell? 8.Is the element stable or unstable?

Chlorine Cl P:17 N:18 1.What is it’s Element Symbol? Cl 2.What is it’s Atomic #? 17 3.How many Protons? 17 4.How many Neutrons? 18 5.How many Electrons? 17 6.Draw a Bohr model of Chlorine 7.How many electrons are in the valence shell? 7 8.Is the element stable or unstable? Stable

Joke of the Day:

Chemical Compounds Compound: A combination of two or more elements. Molecule: the smallest unit of a compound. –Written as a chemical formula. Water is written as H 2 O because it contains two atoms of Hydrogen and one atom of Oxygen. Table Salt is written as NaCl because it has one atom of Sodium and one atom of Chlorine.

Let’s take a look at Chemical Formulas H2OH2O Subscript: Tells you how many of each atom are in the molecule. If there is no subscript, there is one of that atom. 2H 2 O Coefficient: Tells you how many of each molecule you have. If there is no number in front then there is one of that molecule

Count the Atoms!  H  H 2  H 2 O  2H 2 O ***Molecules in parentheses are called Polyatomic Ions and always occur together when they bond.  H 2 (SO 4 )  C 7 H 5 (NO 2 ) 3 = H:1 = H:2 = H:2 O:1 = H:4 O:2 = H:2 S:1 O:4 = C:7 H:5 N:3 O:6

Chemical Bonds Ionic Bonds: Occurs when one or more electrons are transferred from one atom to another. Ion: an atom with a positive or negative charge. Ionic Bond = Giver + Taker Givers won’t bond with Givers

Sodium atom (Na)Chlorine atom (Cl)Sodium ion (Na + )Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1 Ionic Bonds

Chemical Bonds Covalent Bond: Occurs when two atoms share electrons Covalent Bond = Taker + Taker Givers won’t bond with Givers

What is theSpringfield High School Mascot on the Simpsons?

Isotopes Isotopes: Atoms of the same element that differ in the number of neutrons that they contain. –Radioactive Isotopes: Isotopes are unstable and break down at a constant rate over time. Dangerous but has practical uses. Dating rock layers, cancer treatment, food preservation.

Isotopes of Carbon Nonradioactive carbon-12Nonradioactive carbon-13Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 8 neutrons 6 electrons 6 protons 7 neutrons