Chapter 6 Biochemistry The Chemistry of LIFE – preAP Biology Moore High School

Essential Questions What are atoms? How are the particles that make up atoms diagrammed? What are the similarities between covalent and ionic bonds? How are van der Waals forces described? Atoms, Elements, and Compounds Copyright © McGraw-Hill Education

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education A. Atoms The structure of an atom Atoms are the building blocks of matter. Atoms are made up of smaller particles called neutrons, protons, and electrons Protons are positively charged particles (p + ). Neutrons are particles that have no charge (n 0 ). Electrons are negatively charged particles (e - ).

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Atoms The structure of an atom Protons and neutrons are located in the center of the atom, called the nucleus. Electrons are located outside the nucleus.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education B. Elements An element is a pure substance that cannot be broken down into other substances by physical or chemical means. There are over 100 known elements, 92 of which occur naturally. Each element has a unique name and symbol.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Elements 1. The periodic table of elements shows what everything in the universe is made of. Horizontal rows are called periods, vertical columns are called groups.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Elements 2. Isotopes Atoms of the same element that have the same number of protons and electrons but have a different number of neutrons are called isotopes.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Elements 3. Radioactive isotopes Isotopes that give off radiation are called radioactive isotopes. When a nucleus breaks apart, it gives off radiation that can be detected and used for many applications.

Isotopes - Go watch Brainpop in textbook Atoms, Elements, and Compounds Copyright © McGraw-Hill Education

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education C. Compounds 1.A compound is a pure substance formed when two or more different elements combine. 2.Compounds are always formed from a specific combination of elements in a fixed ratio. 3.Compounds cannot be broken down into simpler compounds or elements by physical means, but can be broken down by chemical means.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education D. Chemical Bonds The force that holds substances together is called a chemical bond. The electrons of an atom are responsible for forming chemical bonds. Electrons travel around the nucleus of an atom in areas called energy levels. Atoms become more stable by losing electrons or attracting electrons from other atoms.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Chemical Bonds 1.Covalent bonds The chemical bond that forms when electrons are shared is called a covalent bond. A molecule is a compound in which the atoms are held together by covalent bonds.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Chemical Bonds 2.Ionic Bonds An atom that has lost or gained one or more electrons is an ion. Ions carry an electric charge. An ionic bond is an electrical attraction between two oppositely charged atoms.

Ionic Bonds Animation FPO Add link to concepts in motion animation from page 153 here. Atoms, Elements, and Compounds Copyright © McGraw-Hill Education

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Chemical Bonds Ionic bonds Some atoms tend to donate or accept electrons more easily than other atoms. The elements identified as metals tend to donate electrons. The elements identified as nonmetals tend to accept electrons. Most ionic compounds dissolve in water, are crystalline at room temperature, and have higher melting points than compounds formed by covalent bonds.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education E. van der Waals Forces One type of Weak Attraction between molecules are called van der Waals forces. When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education van der Waals Forces van der Waals forces in water The slightly positive and slightly negative charges around the water molecule are attracted to the opposite charge of other nearby water molecules. van der Waals forces are responsible for water droplet formation and surface tension.

Atoms, Elements, and Compounds Copyright © McGraw-Hill Education Review Essential Questions – Check up from the neck up What are atoms? How are the particles that make up atoms diagrammed? What are the similarities between covalent and ionic bonds? How are van der Waals forces described? Vocabulary *****Choose at least 7 – 10 of these for your foldable atom nucleus proton neutron electron element isotope compound covalent bond molecule ion ionic bond van der Waals force

Chemical reactions allow living things to grow, develop, reproduce, and adapt. Section 2: Chemical Reactions K What I Know W What I Want to Find Out L What I Learned

Essential Questions What are the parts of a chemical reaction? How can energy changes be related to chemical reactions? What is the importance of enzymes in living organisms? Chemical Reactions Copyright © McGraw-Hill Education

Chemical Reactions Copyright © McGraw-Hill Education Reactants and Products A chemical reaction is the process by which atoms or groups of atoms in substances are reorganized into different substances. 1.Chemical bonds are broken or formed during a chemical reaction. 2.Clues that a chemical reaction has taken place: production of heat or light formation of a new gas, liquid, or solid 3.Substances can also undergo physical changes, which change the appearance but not the composition.

Chemical Reactions Copyright © McGraw-Hill Education Reactants and Products Chemical equations In written chemical equations, chemical formulas describe the substances in the reaction and arrows indicate the process of change. Reactants are the starting substances, on the left side of the arrow. Products are the substances formed during the reaction, on the right side of the arrow. The arrow can be read as “yields” or “react to form.”

Chemical Reactions Copyright © McGraw-Hill Education Reactants and Products Chemical equations Balanced equations In chemical reactions, matter cannot be created or destroyed. All chemical equations must show this balance of mass. The number of atoms of each elements on the reactant side must equal the number of atoms of the same element on the product side. C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

Chemical Reactions Copyright © McGraw-Hill Education Energy of Reactions Activation energy The minimum amount of energy needed for reactants to form products is called activation energy. Some reactions rarely happen due to the high activation energy required.

Chemical Reactions Copyright © McGraw-Hill Education Energy of Reactions Energy change in chemical reactions Reactions that release energy in the form of heat are exothermic. Reactions that absorb energy in the form of heat are endothermic.

Chemical Reactions Copyright © McGraw-Hill Education Enzymes 1.Enzymes are catalysts that reduce activation energy and speed up reaction time in living organisms. 2.Catalysts do not change the amount of product produced, and are NOT used up during the reaction. 3. Enzymes are proteins and are specific to a reaction

Chemical Reactions Copyright © McGraw-Hill Education Enzymes The reactants that bind to an enzyme are called substrates. The specific location where a substrate binds on an enzyme is called the active site. Factors such as pH, temperature, and other substances affect enzyme activity.

Chemical Reactions Copyright © McGraw-Hill Education Review – Check up from the neck up Essential Questions What are the parts of a chemical reaction? How can energy changes be related to chemical reactions? What is the importance of enzymes in living organisms? Vocabulary – Section II vocab – Write all 9 vocab words on your foldable chemical reaction reactant product activation energy catalyst enzyme substrate active site