Chemical Reactions. History of the Atomic Theory John Dalton - Billiard ball model  Solid, dense balls with no charge.

Slides:



Advertisements
Similar presentations
Chapters 5 sections 1, 2 & 3 6 sections 2, 3
Advertisements

Unit 1 – Chemical Basis of Life
The Chemical Basis of Life
Atomic Structure and Chemistry. What is matter? Matter is anything that takes takes up space and has mass. May or may not be visible (example.... air)
Warm-up 11/21 Watch the video and describe how one scientists changed aspects of the previous theory to make a new one.
Section 1: Atoms, Bonding, and the Periodic Table
Chapter 8: Elements and Chemical Bonds
A TOMS, B ONDING, AND THE P ERIODIC T ABLE Valence Electrons and Bonding The number of valence electrons (electrons in the outermost energy level) in an.
Basic Food Chemistry: The Nature of Matter
Chemical Bonds & Reactions
Ionic Bonds What is an Ion?
Created by C. Ippolito Dec 2006 Chemical Bonding Objectives: 1.describe the nature of a chemical bond and its relationship to valence electrons 2.compare.
Chemistry in Biology.
Table of Contents Elements and Atoms
Atoms and Bonding The Building Blocks of Matter Matter may consist of elements, compounds, or mixtures. Element: a substance made of only one type of atom.
Unit 2 Ecological Biochemistry
Noggin Knockers Final Jeopardy The Atom Periodic Table Bonding Chemical Formulas Chemical Reactions Real World.
Compounds and Bonds Chapter 2 - Chemical Interaction.
Section 3: Covalent Bonds
Chemical Foundations for Cells Chapter 2. You are chemical, and so is every living and nonliving thing in the universe. You are chemical, and so is every.
Two types of chemical bonds are Ionic Bonds and Covalent Bonds Chemical Bonding: Covalent Bonding.
Valence Electrons: the electron(s) in the outer shell of an atom’s electron cloud, which can combine with other atoms to form molecules *The number.
Chapter 4 Section 1 Matter Objectives
ESCS Review. Composition of Matter (Review) Matter – anything that takes up space and has mass. Mass – the quantity of matter an object has (the same.
Chapter 4- Earth Chemistry
Atoms and Bonding Chapter 5.
Atoms, molecules, bonding, periodic table. Atoms Modern Atom Model Nucleus-Protons and Neutrons Electrons around nucleus, never know the true location.
CHAPTER 2 The Chemistry of Life.
Bonding Ionic Valence Electrons The number of valence electrons in an atom of an element determines the many properties of that element, including the.
The Nature of Molecules Chapter 2. 2 Atomic Structure All matter is composed of atoms. Understanding the structure of atoms is critical to understanding.
Chemical Bonds & Reactions Chemical Bond A force of attraction that holds two atoms together Has a significant effect on chemical and physical.
 Define these words  Ion  Ionic bond  Ionic compound  Chemical formula  Subscript  Covalent bond.
The Chemistry of Living Cells. What are ATOMS? Atoms are the basic building blocks of matter that make up everyday objects. A desk, the air, even you.
The Building Blocks of Matter
Chapter 1 Chemical Bonding. All matter is made up of atoms. Atoms are the basic building blocks of all the substances in the universe.
Chemical Bonds & Formulas Chemical Bond A force of attraction that holds two atoms together Has a significant effect on chemical and physical.
Notes 5-1 Atoms, Bonding and the Periodic Table Key Ideas: How is the reactivity of elements related to valence electrons in atoms? What does the periodic.
Properties of Matter. Element A pure substance that cannot be broken down into simpler substances by ordinary chemical means. Sulfur.
PAP Chapter 6 CHEMICAL BONDING Cocaine. Chemical Bonding  A chemical bond is a mutual electrical attraction between the nuclei and valence electrons.
Eighth Grade Review Chemistry. Matter is anything that has mass and occupies space. All matter is made up of small particles called atoms.
Atoms and Bonding Review. Valence Electrons highest energy level held most loosly number of valence electrons determines many properties, especially how.
Chapter 5 Atoms and Bonding. Valence Electrons and Bonding Valence electrons are those electrons that have the highest energy level and are held most.
WHY DO ATOMS BOND TOGETHER? ATOMS WANT TO ACHIEVE A STABLE ELECTRON CONFIGURATION (OR FULL OUTER SHELL OF VALENCE ELECTRONS).
Physical Science Chapter 6 Chemical Bonds. Bonding Chapter 6 is about different types of atomic bonding Forces of attraction is the key to this bonding.
1. How are the noble gases different from other groups of elements? a. Their atoms do not react easily with other atoms. b. They are nonmetals. c. They.
Chapter 6 Biochemistry The Chemistry of LIFE – preAP Biology Moore High School.
Atoms and Bonding Chapter 5. Valence `and Bonding Valence electrons- electrons on the outermost energy level. The number of valence electrons in an atom.
The 8 valance electrons in the noble gases make them chemically stable All other Elements “want” their valence electron structure to look like a noble.
BASIC CHEMISTRY I thought this was biology? Objective: 1.To Understand what causes chemical bonds 2.To be able to read an equation 3.To Understand polarity.
Valence Electrons: the electron(s) in the outer shell of an atom’s electron cloud, which can combine with other atoms to form molecules *The number.
The Nature of Molecules Chapter 2. 2 Do Now Complete Vocab pre-quiz for Ch 2.
When two or more substances react to produce new compounds with different physical and chemical properties.
Chemical Bonds & Reactions
The Nature of Molecules
PROPERTIES AND CHANGES
Chemical Bonds & Reactions
Chemical Bonds & Reactions
Atoms and Bonding Table of Contents
Chemical Bonds & Reactions
Chemical Bonds & Reactions
Chemical Bonds & Reactions
Atoms and Bonding Table of Contents
Chemical Bonds & Reactions
Chemical Bonds & Reactions
CHEMICAL REACTIONS & CHEMICAL BONDING
Chemical Compounds and Bonds
Chemical Bonds & Reactions
Chemistry Notes Chapter 2
Chapter 6 Chemistry in Biology
Presentation transcript:

Chemical Reactions

History of the Atomic Theory John Dalton - Billiard ball model  Solid, dense balls with no charge.

History of the Atomic Theory JJ Thompson - Plum Pudding Model  Positive nucleus, negative electrons spread spread throughout

History of the Atomic Model Rutherford - Solar System Model  Negatively charged electrons orbit a positively charged nucleus.  Atom is mostly empty space.

History of the Atomic Model Multiple contributors - Modern Atomic Model  Densely packed nucleus with positively charged protons and neutrally charged neutrons.  Negative electrons orbit in specific shells based on their energy level, creating an “electron cloud”

Vocabulary Element- The pure form of a substance (i.e. Neon) Compound- Two or more atoms bonded together to make a new substance (i.e. Calcium carbonate) Mixture- Two or more substances that are mixed together but do not bond chemically (i.e. grains of sand)

Vocabulary Valence electron- Electrons located on the outermost orbit or “shell” of an atom. Covalent bond- A bond made between atoms when they share electrons. (H2O, CO2)  Generally very strong bonds that release large amounts of energy when broken Ionic bond- A bond made between atoms because they have opposite charges. (NaCl, MgO)  Generally a weak bond that does not release much energy when broken.

Vocabulary Polar Covalent Bond- A covalent bond where there is an unequal sharing of electrons, resulting in a slightly positive or slightly negative charge  Can result from stronger attractions of different nuclei, or because of the shape of the molecule that results from the bonding. Metallic Bond- Positively charged metal ions embedded in a “sea” of valence electrons

Chemical Reactions When old bonds break, and/or new bonds form between chemicals, we get a chemical reaction  Chemical reactions result in one or more new chemicals The “goal” of an atom is to get a full valence shell of electrons by accepting, donating or sharing electrons with other atoms.  When atoms work together like this, a chemical bond is created, and a new substance with unique properties results

Valence Electrons When creating the periodic table, Mendeleev noticed that he could group elements by their “combining capacity.” Mendeleev did not know how elements bonded but he was able to observe these changes in substances. By studying the periodic table, we can see why some elements more readily react than others.

Valence Electrons Valence electrons are often symbolized in “dot” diagrams  Each dot around the element shows a valence electron Patterns can be seen when you compare these dot diagrams to the families on the periodic table

Ionic Bonds When an atom loses an electron, it loses a negative charge and becomes a positive ion (cation) When an atom gains an electron, it gains a negative charge and becomes a negative ion (anion)

Ionic Bonds

In general, ionic bonds are hard, brittle compounds that have high melting points and form crystal structures.

Covalent Bonds When the nuclei of two atoms share electrons, we have a covalent (co- meaning together; -valent meaning valence) bond. The force that holds atoms together in covalent bonds is the attraction of the nucleus to a shared pair of electrons.

Covalent Bonds In this molecule, three hydrogen atoms have bonded with one nitrogen. The nitrogen and hydrogen now have a full valence shell.

Covalent Bonds An oxygen molecule contains one double bond, a carbon dioxide molecule contains two double bonds and a nitrogen molecule will contain one triple bond.

Polar Covalent Bonds Sometimes, bonds are shared slightly unequally.  Can result by stronger attractive forces of one atom, or because of the shape the molecule takes. This will result in a “polar” molecule that has a slightly more negative or more positive charge.

Polar Covalent Bonds A carbon dioxide molecule is a nonpolar molecule because of its straight-line shape. In contrast, a water molecule is a polar molecule because of its bent shape. This is why water has surface tension and the properties of adhesion and cohesion.

Metallic Bonds Metallic bonds form when positive metal ions are embedded in a “sea” of electrons. This gives the metal it’s properties of conductivity, malleability, ductility and luster.  Conductivity- Ability to transfer heat and/or electricity  Malleability- The ability of metal to be shaped and pounded into thin sheets (Tin, Aluminum)  Ductility- The ability of a metal to be pulled into thin strands (Copper, Gold)  Luster- The “shine” of a metal (Silver, Gold)

Graphic Organizer FeatureIonic Bond Covalent Bond Polar Covalent Bond Metallic Bond How Bond Forms Attraction between oppositely charged ions Equal sharing of electrons Unequal sharing of electrons Attraction between embedded ions and surrounding electrons Charge on Bonded Atoms? Yes, positive or negative NoYes, slightly positive or slightly negative Yes, positive Example NaCl (table salt) molecule CO 2 moleculeH 2 O moleculeAluminum

Physical vs. Chemical Change Physical changes occur when objects or substances undergo a change that does not change their chemical composition.  Only change the form of a substance Chemical changes occur when objects or substances undergo a change that causes chemical bonds to break and/or form.  Results in one or more new substances

Physical vs. Chemical Changes Physical Shape Size Freezing/ Boiling Hardness Flexibility Density Conductivity Chemical Heat Light Odor Sound Color change Bubbles

Chemical Reactions We have a “shorthand” way of describing chemicals and chemical reactions.  We call this an equation. The shorthand is much like math equations, but instead of an equal sign, we use arrows to show which direction the reaction is moving.

Chemical Reactions The formula of a chemical compound shows what atoms are present and in what ratios.  For example, in a sucrose molecule there are 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms.  Baking soda has one sodium, one hydrogen, one carbon, and three oxygen atoms.

Balancing Equations The Law of Conservation of Mass states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products.  This means that there has to be the same number of the same kinds of atoms on each side of the equation.

Balancing Equations The equation H 2 + O 2 H 2 O is not a balanced equation. In this equation, there are 2 hydrogen and 2 oxygen on the reactants side, but on the products side, there is only one hydrogen and 2 oxygen. How would you balance this equation without changing the molecules on each side?

Try It! Magnesium (Mg) will react with atmospheric oxygen (O 2 ) to produce magnesium oxide (MgO)  1. Write an equation to symbolize this reaction  Mg + O 2 MgO  2. Write a BALANCED equation to symbolize this reaction  2Mg + O 2 2MgO

Try It! Hydrogen peroxide (H 2 O 2 ) will decompose when exposed to light and turn into water (H 2 O) and oxygen (O 2 )  1. Write and equation that shows this reaction.  H 2 O 2 H 2 O + O 2  2. Write a BALANCED equation that shows this reaction.  2H 2 O 2 2H 2 O + O 2

Energy in Reactions When a reaction occurs, energy is either released or absorbed. If energy is released, it is an exothermic (exo- meaning outside, -thermic meaning heat) reaction and the substance gets hot. If energy is absorbed, it is an endothermic (endo- meaning inside, -thermic meaning heat) reaction and the substance cools down.

Energy in Reactions Whether a reaction is exothermic or endothermic, reactions need energy to get started. This is called activation energy

Energy in Reactions Energy, chemicals, substances, or environments that speed up a chemical reaction- but are themselves not part of the reaction- are called catalysts. Even your cells need catalysts to function. Catalysts that are involved in biological processes are often called enzymes. Enzymes in your body are responsible for helping speed up the process of breaking down food in your mouth and your gut, ultimately releasing energy.

Energy in Reactions Cause Effect Increase temperature Increase surface area Increase concentrations of reactants Add a catalyst Increased rate of reaction

Graphic Summary Endothermic reactions Chemical reactions Exothermic reactions Equations Activation energy Chemical symbols Arrows and plus signs Coefficients Can be Are written as Balanced with Which require Written using