Chapter 2

What’s The Matter? All of the materials around you are made up of matter. You are made up of matter, as are the chair you sit on and the air you breathe. 1. Give an example of solid matter. 2. Give an example of liquid matter. 3. Give an example of gaseous matter. 4. Is all matter visible? 5. Does all matter take up space?

Atoms 100 million atoms in row = 1 cm Made of three things Protons Positive charge Found in nucleus Neutrons Neutral charge Found in nucleus Electrons Negative charge Found in cloud around nucleus

Elements and Isotopes Element A pure substance made up of only one type of atom Ex: carbon, oxygen, hydrogen Isotope Atoms of the same element that have a different number of neutrons

In Your Notebook Draw a diagram of a hydrogen atom, which has an atomic number of 1. Look on page 34 if you need help.

Chemical Compounds A substance formed by combining two or more elements. Ex: H2O, NaCl, HCl The physical and chemical properties of a compound are usually very different from the elements from which it is formed. Sodium-Na-very soft and can be cut with knife, it is highly flammable Chlorine-Cl-poisonous, greenish gas used in WWI Put the together and you get NaCl which is table salt We eat it everyday without harm

Chemical Bonds Two types Ionic Covalent

Ionic Bonds Electrons transferred (stolen) from one atom to another Ions = charged atom Ex: Na +, Cl -, Mg 2+

Covalent Bonds Electrons are shared When you join atoms using covalent bonds you form a molecule. It’s the smallest unit of most compounds.

In Your Notebook In your own words, describe the differences between ionic and covalent bonds.

Van der Waals Forces Electrons not evenly shared When molecules are close together they can develop a slight attraction for nearby molecules. Read page 39.

2.2 Water, Water Everywhere If you have ever seen a photograph of Earth from space, you know that much of the planet is covered by water. Water makes life on Earth possible. If life as we know it exists on some other planet, water must be present to support that life. 1. Working with a partner, make a list of ten things that have water in them.

Water, Water Everywhere 2. Exchange your list for the list of another pair of students. Did the two lists contain some of the same things? Did anything on the other list surprise you? 3. Did either list contain any living things?

Characteristics of Water Water is polar and can form hydrogen bonds. There is an uneven distribution of electrons

Characteristics of Water Cohesion Attraction between molecules of the same substance Water likes to stick together – that’s why it forms drops on a smooth surface Surface Tension

Characteristics of Water Adhesion Attraction between molecules of a different substance Water likes to stick to the edges of glass and plastic

Characteristics of Water Heat Capacity Water’s is very high Takes a long time to heat up This is why it is in your car radiator Also takes long time to cool down Protects your body from drastic temperature changes

In Your Notebook 1. What does it mean when a molecule is said to be polar? 2. Describe how hydrogen bonds between water molecules occur.

Solutions and Suspensions Mixture Two or more elements or compounds that are physically mixed together but not chemically combined Ex: salt and pepper sugar and sand air Two types of mixtures: Solutions Suspensions

Solutions and Suspensions Solutions Components are evenly distributed Solute-the substance that is dissolved Solvent-water Saturation-when water has dissolved all it can

Solutions and Suspensions Suspension Materials not dissolved but are suspended in liquid Ex: blood

Acids, Bases and pH H2O H + + OH - water hydrogen ion + hydroxide ion Acidic = more H + Basic = more OH -

Buffers Buffers help prevent drastic changes in pH Adding acid to unbuffered solution causes pH to drop Adding acid to buffered solution only causes slight change

In Your Notebook Order these items in order of increasing acidity: Soap, Lemon Juice, Milk, Acid Rain What is the difference between a solution and a suspension? The acid hydrogen fluoride can be dissolved in pure water. Will the pH of the solution be greater or less than 7?

2.3 Life’s Backbone 1. Write a brief description of what you think fats, proteins, and carbohydrates are. If you know of other elements that are found in these nutrients, write those elements next to the nutrients in which they are found.

The Chemistry of Carbon Carbon has four valence electrons This means it can bond with many elements Ex: hydrogen, oxygen, phosphorus, sulfur and nitrogen Carbon can also bond with itself This allows long chains and rings to be formed

Macromolecules Giant molecules Made from smaller molecules put together Formed by polymerization Large compounds built by joining smaller ones together Monomers join together to make Polymers

Macromolecule #1-Carbohydrates Made of carbon, hydrogen and oxygen in 1:2:1 ratio Used as source of energy and for structure in plants Monosaccharides Single sugar molecule Ex: glucose, galactose Disaccharide Two simple sugars joined Ex: sucrose Polysaccharides Chains of monosaccharides Ex: glycogen, starch, cellulose

Macromolecule #2-Lipids Not soluble in water Store energy Make biological membranes and waterproof coverings Steroids are lipids-they are chemical messengers Have glycerol head and fatty acid chains Saturated Carbons joined by single bond Unsaturated One carbon double bond Polyunsaturated More than one carbon double bond

In Your Notebook Answer the questions in the analyzing data section on page 48

Macromolecule #3-Nucleic Acids Contain hydrogen, oxygen, nitrogen, carbon and phosphorus Store and transmit genetic information Made of nucleotides Two types RNA DNA

Macromolecule #4-Proteins Made of nitrogen, carbon, hydrogen and oxygen Polymers of amino acids Control rates of reactions Regulate cell processes Form cell structures Transport substances in and out of cell Help fight disease

In Your Notebook What properties of carbon explain carbon’s ability to form different large and complex structures? Name the four groups of organic compounds (macromolecules) found in living things. Explain the relationship between monomers and polymers.

2.4 Matter and Energy Have you ever sat around a campfire or watched flames flicker in a fireplace? The burning of wood is a chemical reaction—a process that changes one set of chemicals into another set of chemicals. 1. Wood doesn’t burn all by itself. What must you do to start a fire? What does this mean in terms of energy? 2. Once the fire gets started, it keeps burning. Why don’t you need to keep restarting the fire?

Chemical Reactions A process that changes one set of chemicals into another. Reactant The elements you start with Product What you end up with Everything that happens in your body is based on chemical reactions

Energy in Reactions Energy is either released or absorbed Spontaneous Reactions Happen on their own Energy is released Ex: burning of hydrogen Chemical reactions that absorb energy will not occur on their own. Activation Energy Energy needed to start a reaction

In Your Notebook What happens to chemical bonds during chemical reactions? What is activation energy? Describe the difference between a reaction that occurs spontaneously and one that does not.

Enzymes Proteins that act as biological catalysts. Catalyst = a substance that speeds up the rate of chemical reactions

Enzymes Do we really need them? CO2 + H2O H2CO3 This reaction removes carbon dioxide from bloodstream. But, it’s very slow. Our body has catalyst known as carbonic anhydrase that speeds this reaction up by a factor of 10 million.

Enzyme-Substrate Complex Place for the chemical reaction to happen Brings the reactants (substrates) together Less energy is needed if they are close by

Regulation of Enzyme Activity Affected by temperature, pH and regulatory molecules Ex: In humans most enzymes work best at 98.6F If you get a fever your body processes slow down because the enzymes don’t work and all of the chemical reactions are slowed. The enzymes lose their shape and no longer fit with the substrates. The key no longer fits in the lock.

In Your Notebook One Minute Response: What role do enzymes play in living things?