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WGU C190- Biology Unit 2 Exam Questions and Complete Solutions Graded A+
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WGU C190- Biology Unit 2 Exam Questions and Complete Solutions Graded A+
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WGU C190- Biology Unit 2 ExamQuestions and Complete Solutions
Graded A+
Parts of the Atom - Answer: - protons, neutrons, and electrons are the 3 basic particles that make up an
atom
Protons - Answer: - positively charged subatomic particles
- have a mass of one atomic mass unit (amu)
Neutrons - Answer: - the particles of the nucleus that have no charge
- have a mass of one atomic mass unit (amu)
What makes up the nucleus or center of the atom? - Answer: - Protons and neutrons
- Because both the proton and neutron are in the nucleus, the nucleus has a positive overall charge.
Electrons - Answer: - negatively charged subatomic particles
- Electrons have almost no mass (0 amu) and are found outside of the nucleus, in zones that are called
shells.
These shells are filled up in a specific way. The shells closest to the nucleus are filled first, and then
additional shells are filled as needed. The first shell has room for two electrons.
Both the second and third shells have room for eight electrons each.
,How do you determine the charge of an atom? - Answer: - When the number of protons equals the total
number of electrons, then the atom is electrically neutral. If the number of electrons differs from the
number of protons, then the atom has an electrical charge. That is, if there are more protons, it will be
positively charged; if there are more electrons, it will be negatively charged.
An atom with a positive charge or a negative charge is called an ion.
An atom has six electrons and is electrically neutral. How many protons does the atom have? - Answer: -
6
- To be electrically neutral, the atom must have the same number of protons as electrons.
An atom has 17 protons and 18 electrons. Is this atom an ion? - Answer: - Yes
- It has unequal numbers of protons and electrons.
If an atom has three protons and two electrons, what is the charge of the atom? - Answer: - +1
- Three protons would have a charge of +3, and two electrons would have a charge of -2.
- +3 + (-2) = +1
Periodic Table of Elements - Answer: - A table that classifies elements by their physical and chemical
properties; rows are called periods; columns are called groups
- The atomic number of an element is equal to the number of protons it has. Example: Nitrogen (N) has
an atomic number of 7 meaning it has 7 protons within it's nucleus
In biological systems, what are the major elements? - Answer: - carbon (C), hydrogen (H), nitrogen (N),
oxygen (O), phosphorus (P), and sulfur (S). These elements represent more than 95% of the mass of a
cell
, Trace Elements - Answer: - elements found in relatively small amounts
- Examples include sodium (Na), potassium (K), chlorine (Cl), manganese (Mn), and Zinc (Zn).
- Very important for the functioning of a cell
Covalent bond - Answer: - A strong chemical bond formed when two atoms share electrons
Ionic bond - Answer: - A chemical bond resulting from the attraction between oppositely charged ions.
- This moderately strong bond happens when an electron transfers from one atom to another to create
an electrostatic attraction between the two oppositely charged ions
Hydrogen bond - Answer: - Attraction between a slightly positive hydrogen atom and a slightly negative
atom.
- A weak bond occurring between atoms in different molecules or parts of molecules
What is the "glue" that holds covalently bonded atoms together? - Answer: - One or more electrons that
are shared between the two atoms
What determines the type of bond that will form between atoms? - Answer: - Atoms tend to bond to
other atoms in such a way that both atoms have filled outer shells as a result of the interaction.
- Remember that electrons orbit around the nucleus in a specific pattern. They fill shells closest to the
nucleus before filling shells further away. The first shell has room for two electrons, and the second and
third shells have room for eight each. The most stable situation for an atom is to have its outer shell
completely filled with electrons.
- Example: if sharing electrons provides that stability, then the two atoms will form a covalent bond.
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