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Chapter 6 Part 2 Pages 145-151.

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Presentation on theme: "Chapter 6 Part 2 Pages 145-151."— Presentation transcript:

1 Chapter 6 Part 2 Pages

2 Compounds and Bonding Page 145 Compound- a substance that is composed of atoms of two or more different elements that are chemically combined

3 Most elements in nature are found combined in the form of compounds
How and why do atoms combine? Combine when the resulting compound is more stable than the individual atoms. For many elements, an atom becomes more stable when its outermost energy level is full- by sharing electrons with other atoms

4 Sharing electrons

5 Page 146 Covalent bond- force that holds atoms together when they are sharing electrons Most compounds in organisms have covalent bonds.

6 Molecule A group of atoms held together by covalent bonds.
No overall charge Example-molecule of water

7 Chemical formula Page 147 Use the chemical symbol for atoms
Subscripts represent the number of atoms present Example:

8 Ionic Bonds An atom gains or loses electrons, it has an electrical charge (charged particle) and will assume the name ION. atoms combine with each other by gaining or losing electrons in their outer energy levels- not sharing of electrons Example page 147- sodium chloride

9 Chemical Reactions Page 147
Occur when bonds are formed or broken, causing substances to recombine into different substances All of the chemical reactions that occur within an organism are referred to as that organism’s metabolism Consists of reactants and products

10 Chemical Equations Reactants Products
Number before each formula indicates the number of molecules of each substance Subscripts in a formula indicate the number of atoms of each element in a molecule of the substance Equations must always balance



13 Mixtures Page 148 A mixture is a combination of substances in which the individual components retain their own properties Example- mixing sand and sugar crystals

14 Solutions A mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent)

15 Acids and Bases Page 149 Chemical reactions can occur ONLY when the conditions are right Variables may include (but not limited to): Temperature Energy availability Solute concentration pH

16 A measure of how acidic or basic a solution is
pH A measure of how acidic or basic a solution is

17 What is an acid? Any substance that forms hydrogen ions in water
Reacts with most metals Tastes sour Frequently feels sticky Examples: grapefruit, oranges, lemon, tomato, milk

18 What is a base? Any substance that forms hydroxide ions in water
Feels slippery Tastes bitter Examples: egg, antacid, ammonia, cleaners


20 Acids and Bases A scale with values ranging from 0 to 14 is used to measure pH 0-6 acidic 7 neutral (pure water) 8-14 basic

21 Acids and Bases Video 8 minutes

22 BIG PICTURE An acid is any substance that form hydrogen ions (H+) in water A base is any substance that forms hydroxide ions (OH-) in water Mini lab 6.1

23 LAB- Analysis Questions
1. What would happen to our bodies if blood pH was changed or altered? 2. The pH of stomach acid is 2, why is this both good but possibly destructive to our bodies? 3. What could happen to our local environment if a company pumped materials into the atmosphere which created a drastic pH change in the rain water?

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