AP Bio Chapter 2 Reading Guide

6 CO2 + 6 H2O --> C6H12O6 + 6 O2 -For the equation you just wrote, how many molecules of carbon dioxide are there? -How many molecules of glucose? -How many elements in glucose?

-6 -1 -3

What is the difference between an essential element and a trace element?

-essential elements: elements that an organism needs to live a healthy life (they comprise about 20-25% of the 92 natural elements) -trace elements: elements required by organisms in only minute quantities (ex. iron-Fe)

-Is O2 a molecule? -compound? -What is O2's molecular formula? -structural formula?

-yes -no -O2 -O=O

-Is methane a molecule? -compound? -What is methane's molecular formula? -structural formula?

-yes -yes -CH4 - H | H -C- H | H

-Is carbon dioxide a molecule? -compound? -What is carbon dioxide's molecular formula? -structural formula?

-yes -yes -CO2 -O=C=O

-Is water a molecule? -compound? -What is water's molecular formula? -structural formula?

-yes -yes -H2O -H-O-H (with a bend)

Be able to find the atomic mass, atomic number, number of electrons, and neutrons of an atom from the periodic table. -find carbon

12.011, 6, 6, 6

What is the atomic number of helium? Its atomic mass?

2 4.003

Define molecule

2 or more atoms held together by a covalent bond

Write the chemical shorthand equation for photosynthesis. Label the reactants and the products.

6 CO2 + 6 H2O --> C6H12O6 + 6 O2 Reactants Products

What is a hydrogen bond? Indicate where the hydrogen bond occurs in this figure. -Diagram of molecules are on reading guide question 22

A hydrogen bond is a noncovalent attraction between the hydrogen of one molecule with the oxygen or nitrogen of another molecule. There are no hydrogen bonds in a single molecule of water, but the hydrogens of one water molecule will hydrogen bond with the oxygen of another.

Define anion and cation. In the preceding example, which is the anion?

Anion is a negatively charged ion. Cation is a positively charged ion. In the preceding example, chloride ions are the anion, and sodium ions are the cation.

Here is a list of the types of bonds and interactions discussed in this section. Place them in order from the strongest to the weakest: hydrogen bonds, van der Waals interactions, covalent bonds, ionic bonds

Covalent bonds Ionic bonds Hydrogen bonds Van der Waals interactions

Make an electron distribution diagram of water. Which element is most electronegative? Why is water considered a polar molecule? Label the regions that are more positive or more negative. (This is a very important concept. Spend some time with this one!)

Diagram on Reading Guide Question 18 Explanation: Water is considered a polar molecule because oxygen is more electronegative than hydrogen, and therefore the shared electrons are pulled more toward oxygen. :

What is meant by dynamic equilibrium? Does this imply equal concentrations of each reactant and product?

Dynamic equilibrium means that reactions are still going on, but with no net effect on the concentrations of the reactants and products. Equilibrium does not mean that the reactants and products are equal in concentration, but only that their concentrations have stabilized at a particular ratio.

sketch a model of a helium atom

Look of reading guide, question 4

Explain van der Waals interactions. Though they represent very weak attractions, when these interactions are numerous they can stick a gecko to the ceiling!

Molecules with nonpolar covalent bonds may have positively and negatively charged ions. Electrons are not always symmetrically distributed in such a molecule and may accumulate by chance in one part of the molecule, resulting in regions of positive and negative charges. These ever-changing regions of positive and negative charge enable all atoms and molecules to stick to one another. These van der Waals interactions are individually weak, and occur only when atoms and molecules are very close together, but can be powerful when many such interactions occur simultaneously.

Explain the difference between a nonpolar covalent bond and a polar covalent bond?

Nonpolar covalent bonds occur between atoms of the same element, the electrons are shared equally, and therefore their polarity is neutral. Polar covalent bonds occur when one atom is bonded to a more electronegative atom, and the electrons of the bond are not shared equally. For example, the bond between the oxygen and hydrogen atoms of a water molecule is a polar covalent bond.

Another bond type is the ionic bond. Explain what is happening in the following figure below -Diagram to do this problem in on reading Guide Question 19

This figure represents electron transfer and ionic bonding. The lone valence electron of a sodium atom is transferred to join the 7 valence electrons of a chlorine atom. Each resulting ion has a completed valence shell. An ionic bond can form between the oppositely charged ions, forming sodium chloride, NaCl.

Define and give an example of compound

a substance consisting of 2 or more elements in a fixed ratio ( table salt-NaCl)

Define and give an example of element

a substance that can't be broken down into other substances by chemical reactions, 92 naturally occurring elements ( oxygen, carbon)

Define and give an example of matter

anything that takes up space and has mass (humans, rocks)

Define atomic mass

approximation of the total mass of an atom (measured in Daltons)

What is meant by electronegativity?

attraction of an atom for the shared electrons of a covalent bond

Which has more potential energy and why? boy at the top of a slide/boy at the bottom

boy at the top of a slide because he is higher up

What 4 elements make up 96% of all living matter?

carbon, oxygen, hydrogen, nitrogen

Define isotope

different atomic formations of the same element, having more neutrons than other atoms of the same element therefore has greater mass

What type of bond is seen in O2? Explain what this means.

double covalent bond. 2 oxygen atoms form a molecule by sharing 2 pairs of valence electrons

Which has more potential energy and why? electron in he first energy shell/electron in the third energy shell

electron in the third energy shell because of its relative distance from the nucleus so the pull isn't as strong

Which is the only subatomic particle that is directly involved in the chemical reactions between atoms?

electrons

What is potential energy?

energy that matter possessed because of its location or structure

Which has more potential energy and why? water/glucose

glucose because glucose has more bonds than water and chemical bonds store energy

Define atomic number

number of protons in the nucleus of a specific element, ad well as the number of electrons in an electrically neutral atom

Know how to find the number of valence electrons and protons of an atom from an electron distribution diagram.

question 12

Define electron shell

represents the average distance from the nucleus and energy level of electrons circling the nucleus of an atom

What 2 elements are involved above? Look at the diagram from Question 19

sodium (Na) and chlorine (Cl)

Define neutron

subatomic particle that is electrically neutral

Define electron

subatomic particle with one unit of negative charge

Define proton

subatomic particle with one unit of positive charge

Define energy

the capacity to cause change (ex. by doing work)

What determines the chemical behavior of an atom?

the distribution of electrons in the atom's electron shells

Use morphine and endorphins as examples to explain why molecular shape is crucial in biology.

the molecular shape determines how biological molecules recognize and respond to one another with specificity. Morphine and other opiates have similar shape to endorphins, and can therefore mimic the pain-relieving effect of endorphins by binding to endorphin receptors in the brain.