Guided Reading Chapter 2: Essential Chemistry for Biology

How long does it take for approximately 75% of carbon-14 to decay into carbon-12 (in thousands of years)?

11,4000 years

What is the difference in [H+] between urine and lemon juice?

4

regarding acids and bases a. Effect on H+ when dissolved in H2O: Increases H+ b. pH < 7 c. Effect on H+ when dissolved in H2O: decreases H+ d. bleach e. coffee f. pH>7

a. acids b. acids c. bases d. bases e. acids f. bases

Match the following terms with their correct definitions: matter, atom, molecule, element, and compound. a. the smallest unit of matter that retains the properties of their specific type of matter b. a substance that cannot be broken into a simpler substance c. anything that occupies space and takes up mass d. substances with two or more elements in a fixed ratio e. atoms that are bonded to one another covalently

a. atom b. element c. matter d. compound e. molecule

Match the following terms to the proper characteristic: nucleus, proton, electron, neutron, and subatomic particles. Some terms may be used more than once and some characteristics may use multiple terms. a. has almost no mass b. found in the nucleus c. center of an atom d. in constant motion e. protons, electrons, and neutrons

a. electrons b. protons and neutrons c. nucleus d. electrons e. subatomic particles

You add a negatively charged substance to the water molecules. How would you predict that the negatively charged substance would orient itself around the water molecules?

attracted

an attractive force that holds two atoms together is generically referred to as a(n)

chemical bond

Complete the following questions as you read the second chapter content—Water and Life: Which of the following is a unique property of water?

cohesion

Neapolitan ice cream is vanilla, chocolate, and strawberry combined in a 1:1:1 ratio. It is a __________

compound

As the pH increases the [H+] ____________, and as the pH decreases the [H+] ____________.

decreases; increases

evaporative cooling is when a substance evaporates and the surface of the remaining liquid warms the body

false

Which of the following describes atoms of an element that vary in the number of neutrons?

isotopes

Is H2O an element?

no

List the elements (4) make up the majority of a human body.

oxygen, carbon, hydrogen, oxygen

Where can you find all of the elements listed by their atomic number?

periodic table of the elements

An atom comprises what three subatomic particles?

protons, neutrons, electrons

In the following chemical equation, identify the products and reactants and indicate whether or not the equation is balanced. If not, balance the chemical equation.6CO2 + 6H2O---->C6H12O6 + 6O2

the reactants are CO2 and H2O. The products are C6H12O6 and O2

"Navy coffee" is where the coffee is brewed strong and a bit of salt is added. What is special about water that allows you to put sugar or salt in your coffee? To help answer this question, consider the opposite situation: Why do salt scrubs that you buy in a high-end spa consist of large salt crystals in oil? The water in coffee is polar (charged) and allows for other charged substances such as salt and sugar to be dissolved in/by the water. In a salt scrub, you want the salts to be used as an abrasive substance on your skin. If the sale were dissolved, this would not happen. As such, the salt crystals are packed in oil because the oil is nonpolar and will not dissolve the salt because the salt is polar.

true

A radioactive isotope is unstable, which means it gives off energy and particles. If false, make it a correct statement.

true

Chemical reactions are transformations of matter that result in new substances being made by breaking existing chemical bonds, rearranging the atoms into new substances, and forming new chemical bonds.

true

Oils are nonpolar substances (molecules formed by nonpolar covalent bonds) that do not interact with water. Propose an explanation for why oils are not attracted to water, whereas a substance like NaCl (table salt) is attracted to H2O. When answering this question, ask yourself the following: Is NaCl charged? Oils are not attracted to water because they have no slightly charged regions for the water to be attracted to. NaCl is attracted to water because it is polar (charged) so the oppositely charged regions of the water and NaCl are attracted to each other.

true

Radiometric dating provides support for the theory of evolution by natural selection by providing data with which to construct the fossil record. In turn, the fossil record is used to help construct the evolutionary relationships of organisms and their ancestors (and descendants).

true

The pH in your cells is decreasing. Cells have buffers to minimize changes in pH. Briefly explain what the buffer would do in this situation with respect to the H+ concentration in your cells. If the pH is decreasing, then the buffer would accept H+ from the solution. In doing so, the buffer would bring the pH back up by decreasing the amount of H+ in the solution.

true