1. Describe the structure of an atom. Atoms are made up of protons and neutrons in a nucleus. Electrons are in constant motion in the space around the nucleus.2. Why do all isotopes of an element have the same chemical properties They have the same number of electrons
3. What is a covalent bond? A bond formed when electrons are shared between atoms4. What is a compound? How are they related to molecules A compound is a substance formed by the chemical combination of two or more elements in definite proportions. A molecule is the smallest unit of most compounds
5. How do Van der Waals forces hold molecules together? When the sharing of electrons are unequal, a molecule has regions that are charged. An attraction can occur between oppositely charged regions of nearby molecules
6. How are ionic bonds and Van der Waals forces similar? How are they different? In both cases, particles are held together by attractions between opposite charges. The difference is that ionic charges are stronger
Objectives• Why are water molecules polar?• What are acidic solutions? What are basic solutions?
The Big Idea• Much of our planet is covered in water• Water is necessary for life to exist• If life exists on other planets, there most likely is water present• Water has many properties that make life possible
Polarity (-) The oxygen atom has a stronger attraction for electrons (+)
Hydrogen Bonds• Because of waters partial charges, they can attract each other and create hydrogen bonds• Not as strong as covalent or ionic bonds• Waters ability to create multiple hydrogen bonds gives it many special properties
Cohesion• Attraction between molecules of the same substance
Adhesion• Attraction molecules of different substances
Mixture• Material composed of two or more elements or compounds that are physically mixed but not chemically combined• Ex.) salt & pepper, earths atmosphere
Solutions• Mixture of two or more substances in which the molecules are evenly distributed• Ex.) salt water• Settles out over time
1. Use the structure of a water molecule to explain why its polar Oxygen atom has greater attraction for electrons, therefore the oxygen atom is negative and the hydrogen end is positive
2. Compare acidic and basic solutions in terms of their H+ ion and OH- ion concentrations Acid have more H+ ions than OH- ions, and bases have more OH- ions than H+ ions
3. What is the difference between a solution and a suspension? In a solution, all components are evenly distributed. In a suspension, un-dissolved particles are suspended
4. What does pH measure? The concentration of H+ ions in a solution5. The strong acid hydrogen floride (HF) can be dissolved in pure water. Will the pH of the solution be greater or less than 7? less than 7
Objective• What are the functions of each group of organic compounds?
Interest Grabber Section 2-3 Life’s backbone• Most of the compounds that make up living things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms.• As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain.
• More than 20 different amino acids, can join to any other amino acid• The instructions for arranging amino acids into many different proteins are stored in DNA• Each protein has a specific role• The shape of proteins can be very important
1. Name four groups of organic compounds found in living things carbohydrate, lipid, protein, nucleic acids2. Describe at least one function of each group of organic compounds carbohydrates – energy lipids – store energy proteins – form tissue nucleic acids – transmit hereditary information
3. Compare the structures and functions of lipids and starches Lipids are made from carbon and hydrogen. Starches are made of carbon, hydrogen and oxygen. They both can be used to store energy
Enzyme ADP (hexokinase) Glucose SubstratesProducts ATP Glucose-6- phosphate Products Active site are released Substrates Enzyme-substrate bind to complex enzyme Substrates are converted into products
Regulation of Enzyme Activity• Enzymes are affected by any variable that affects chemical reactions1. pH2. Temperature3. Concentration of enzyme
1. What happens to chemical bonds during chemical reactions Bonds are broken in reactants and new bonds are formed in products2. Describe the role of energy in chemical reactions some chemical reactions release energy, and other chemical reactions absorb energy. Energy changes determine how easily a chemical reaction will occur
3. What are enzymes, and how are they important to living things? Enzymes are biological catylasts. Cells use enzymes to speed up virtually every important chemical reaction that takes place in cells
4. Describe how enzymes work, including the role of the enzyme substrate complex Substrates, the reactants of an enzyme-catylzed reaction, attach to the enzyme at an active site and form an enzyme – substrate complex. Once the complex is formed, the enzyme helps convert substrate into product
5. A change in pH can change the protein. How might a change in pH affect the function of an enzyme such as hexokinase (hint: think about the analogy of the lock and key) A change in pH could change the shape of hexokinase. This change would diminish the ability of glucose and ATP to bind to the active site of the enzyme.