2.5 Chapter Resources
Summary
Matter is anything that occupies space and has mass. It is made up of atoms of different elements. Elements that occur naturally have unique qualities that allow them to combine in various ways to create compounds or molecules. Atoms, which consist of protons, neutrons, and electrons, are the smallest units of an element that retain all of the properties of that element. Electrons can be donated or shared between atoms to create bonds, including ionic, covalent, and hydrogen bonds. The pH of a solution is a measure of the concentration of hydrogen ions in the solution. Living things are carbon-based because carbon plays such a prominent role in the chemistry of living things.
Mineral nutrients are cycled through ecosystems and their environment in biogeochemical cycles. Of particular importance are water, carbon, nitrogen, phosphorus, and sulfur. All of these cycles have major impacts on ecosystem structure and function. Ecosystems have been damaged by a variety of human activities that alter the natural biogeochemical cycles due to pollution, oil spills, and events causing global climate change.
Cells are the smallest unit of life, and they run on the chemical energy found mainly in carbohydrate molecules (food). The majority of these molecules are produced by one process: photosynthesis. Through photosynthesis, certain organisms convert solar energy (sunlight) into chemical energy. Directly or indirectly, the process of photosynthesis provides most of the energy required by living things on earth. Photosynthesis also results in the release of oxygen into the atmosphere. In short, to eat and breathe, humans depend almost entirely on the organisms that carry out photosynthesis.
While the chemical energy is produced by photosynthesis, all the other organisms which can’t make their own must acquire it by eating other organism. Energy is transferred between trophic levels as the energy flows from the base to the top of the food web as animals eat each other, with energy being lost (used by those animals to live, eat, and grow) at each transfer.
Review Questions
1. You analyze a sample of carbon and determine that 6% of the carbon atoms in your sample have a mass number (atomic mass) greater than 12, (12 is the normal atomic mass of carbon). Based on these results, which of the following can you reasonably conclude?
A. 6% of the carbon sample is a different element
B. 6% of the sample is comprised of carbon isotopes
C. 6% of the sample is comprised of carbon ions
D. 94% of the sample is comprised of carbon radioisotopes
E. 94% of the sample contains covalent bonds
2. An atom that has an electrical charge due to having a number of electrons unequal to the number of protons is considered a(n)…
A. Isotope
B. Ion
C. Element
D. Molecule
E. Acid
3. The atomic number for the element fluorine is 9 and its mass number is 19. How many neutrons does a normal atom of fluorine have?
A. 0
B. 9
C. 10
D. 19
E. Impossible to determine wi