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Download Block 1 and 2 The Nature of Matter
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• http://www.youtube.com/watch?v=zKNZjP 9BdCw Unit 2: Biochemistry – ATOMS! The Nature of Matter! 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 Math Sub-Atomic Particle Mass Charge Proton Neutron Electron 1 1 0 +1 0 -1 Atomic Number The Atom Helium 2 Element Symbol He Helium Element Name 4 Atomic Mass 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. Mendeleev You can determine the number of protons, neutrons, and electrons using the Periodic table. = number of protons Atomic Number = number of electrons 6 C Carbon 12 Element Symbol Element Name Atomic Mass = number of protons + number of neutrons Let’s Try It! The Atom Helium Atomic Number rotons= 2 Electrons= 2 Neutrons= 4 - 2 Helium has two protons, two electrons, two neutrons =2 2 He Helium 4 Element Symbol Element Name Atomic Mass The Atom Helium Nucleus : Contains Protons and Neutrons Shell contains Electrons e He P:2 N:2 e Electron Shell : Energy Levels Energy Levels: in electron cloud 1st Energy Level = Max. of 2 electrons 2nd Energy Level = Max. of 8 electrons 3rd Energy Level = Max. of 8 electrons 4th Energy Level = Max. of 18 electrons Electron in 1st energy level Electron in 2nd energy level Electron in 3rd energy level Nucleus Valence Electrons Valence electrons: electrons in the outer most energy level = valence electrons- 8 red dots in outer energy level Niels Bohr e e e P:5 B N:6 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 P:5 go inside nucleus go in electron shell B N:6 The Nucleus contains 5 protons and 6 neutrons P:5 B N:6 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 2nd energy level. Valence Electrons: There are 3 valence electrons. To determine this, we look at the outer most energy level (in this case the 2nd level). Then we count the number of electrons. There are 3 electrons on the 2nd energy level. Boron REMEMBER… ALWAYS FILL THE INNER ENERGY LEVELS FIRST!!! START ST WITH THE 1 ENERGY LEVEL! Draw an atom of… Sodium: Na Atomic #: 11 Atomic Mass: 23 Determine… Protons ( + ) = 11 Neutrons ( 0 ) =12 Electrons ( - ) = 11 Valence Electrons? = 1 P:11 Na N:12 Draw an atom of… Beryllium: Be Atomic #: 4 Atomic Mass: 9 Determine… Protons ( + ) = 4 Neutrons ( 0 ) = 5 Electrons ( - ) = 4 Valence Electrons? = 2 P:4 Be N:5 Draw an atom of… Neon: Ne Atomic #: 10 Atomic Mass: 20 Determine… P:10 Protons ( + ) = 10 Ne N:10 Neutrons ( 0 ) =10 Electrons ( - ) = 10 Valence Electrons? = 8 NEON IS A STABLE ELEMENT (OR UNREACTIVE) BECAUSE IT’S OUTER ENERGY LEVEL IS FULL!!! 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 1. 2. 3. 4. 5. 6. 7. 8. What is it’s Element Symbol? Cl What is it’s Atomic #? 17 How many Protons? 17 How many Neutrons? 18 How many Electrons? 17 Draw a Bohr model of Chlorine How many electrons are in the valence shell? 7 Is the element stable or unstable? Stable Cl P:17 N:18 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 H2O 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 H 2O Subscript: Tells you how many of each atom are in the molecule. If there is no subscript, there is one of that atom. 2H2O 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:1 H2 = H:2 H2O = H:2 O:1 2H2O = H:4 O:2 ***Molecules in parentheses are called Polyatomic Ions and always occur together when they bond. H2(SO4) = H:2 S:1 O:4 C7H5(NO2)3 = 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 Ionic Bonds 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 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-12 Nonradioactive carbon-13 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons Radioactive carbon-14 6 electrons 6 protons 8 neutrons