Understand basic chemistry - AP Biology

consists of a ion bonded to a ion, which is a perchlorate ion. Hence, the name of the ion's corresponding acid would be perchloric acid.

Remember, the number of protons is equal to the atomic number of the element. Look at the periodic table and find the element with atomic number 42, it corresponds to molybdenum.

Since atoms are neutral, the number of electrons must equal the number of protons (to balance the negative and positive charges). Thus the element with 17 electrons also has 17 protons. The number of protons is equal to the atomic number of the element. Use the periodic table to find the element with atomic number 17, chlorine. Note that ions are not neutral, thus they have unequal numbers of protons and electrons. Also, isotopes of the same element contain differing numbers of neutrons, which also affects the weight of the isotope.

An electron donor is a reducing agent. That is because it is causing another substance (the electron acceptor) to be reduced. The electron acceptor is called the oxidizing agent. Recall the mnemonic: OIL RIG; Oxidation Is Loss of electrons, Reduction Is Gain of electrons. Acids and bases involve the exchange of electron pairs, or hydrogens not single electrons.

When a substance acts as an electron acceptor it is an oxidizing agent. This is because it causes the oxidation of the substance from which it accepted the electron upon accepting an electron. If the substance acts as an electron donor then it is a reducing agent. Recall the mnemonic: OIL RIG; Oxidation Is Loss of electrons, Reduction Is Gain of electrons.

Since substance A is losing an electron it is undergoing oxidation (oxidation is loss of electrons). Substance B is gaining an electron and so it is undergoing reduction (reduction is gain of electrons). Substance A is the reducing agent because it causes the reduction of substance B, and substance B is the oxidizing agent because it causes the oxidation of substance A.

Since substance B is losing an electron it is undergoing oxidation (oxidation is loss of electrons). Substance A is gaining an electron and so it is undergoing reduction (reduction is gain of electrons). Substance B is the reducing agent because it causes the reduction of substance A, and substance A is the oxidizing agent because it causes the oxidation of substance B.

Since substance A ends up being positively charged, that means it must have lost or donated a negatively charged electron, thus it is oxidized and, is the reducing agent. Substance B ends up being negatively charged, so that means it gained an negatively charged electron, thus it is reduced and, is the oxidizing agent.

Since substance A ends up being positively charged, that means it must have lost or donated a negatively charged electron, thus it is oxidized and, is the reducing agent. Substance B ends up being negatively charged, so that means it gained an negatively charged electron, thus it is reduced and, is the oxidizing agent.

Isotopes are variations of an element that differ by the number of neutrons in the nucleus. Neutrons are neutrally charged, so adding or removing them from a nucleus does not alter the charge of the atom. The atomic number is the number of protons in an atom, and the mass number is the sum of both protons and neutrons in the nucleus. As a result, the mass number will change by adding a neutron.

The number of protons is equal to the atomic number of the element. Adding or subtracting protons will change the element's identity. Ions can be created by changing the number of electrons and isotopes can be created by changing the number neutrons, but changing the number of protons changes the element.

Ions are atoms that have gained or lost electrons. This results in an atom with a charge. Atoms with a neutral charge have an equal number of protons and electrons. Changing the electron number will result in a charge on the atom.

For example, adding an electron to chlorine creates a chlorine anion.

.. ..

:F — B — F: Boron can have a violated octet (6 e-) and each F has 3 lone pairs

.. | .. for a total of 9 pairs of unpaired electrons

:F:

..

Electronegativity is defined as the tendency of an atom to attract an electron in a bond that it shares with another atom. Because oxygen wants to receive two elctrons, while both sodiums wish to lose one electron, oxygen has a higher electronegativity than sodium. Typically, electronegativity can be seen as increasing as you go to the top right of the periodic table. For example, fluorine has a higher electronegativity than nitrogen.

In , the nitrogen is bound covalently to the three oxygens, and the complex has an overall of .

Sodium has a charge of , and is ionically bound to the complex.

When put into water, the compound will dissociate into and .

HCl is an ionic compound, while the other answer choices have only covalent bonds.

We should first remember the difference between sulfate, sulfite, and sulfide. Sulfate is , sulfite is ` and sulfide is .

The only answer choices that could be right must have in them. We then need to see that barium usually has a charge of , as the periodic table shows us, and so we need a charge of to cancel that out. The answer is .

The octet rule requires that each atom in the molecule has eight valence electrons, fully filling the s and p subshells. Atoms that have a full octet tend to be more stable and lower in energy.

In the compound , each fluorine has seven initial valence electrons and boron has three initial valence electrons. Upon forming the compound bonds, boron shares its three electrons with each fluorine through covalent bonds. This givens each fluorine a full octet, but leave boron with only three covalent bonds, resulting in only six valence electrons. Boron does not satisfy the octet rule in this compound.

Each atom in the other listed compounds forms bonds to generate a full octet. Sodium chloride achieves this through an ionic bond. Methanal and diatomic oxygen both use double bonds to help achieve octets.

Ethene is an organic molecule composed of two carbon atoms, joined by a double bond, and four hydrogen atoms.

Ethene, like all molecules, exhibits London dispersion forces. This molecule, however, has no net dipole moment, so it will not exhibit dipole-dipole attraction. Also, even though it contains hydrogens, it does not exhibit hydrogen bonding. To exhibit hydrogen bonding, the hydrogen atoms must be attached to more electronegative atoms, namely nitrogen, fluorine, or oxygen. Finally, ionic bonding is only present in ionic compounds, not organic compounds.

Ionic chemical compounds are always named with the metal before the non-metal. The correct way to name sodium chloride would be , and not , because sodium is the metal and chloride is the non-metal.

All the other examples have the metal before the non-metal. The other answer choices correspond to potassium chloride, magnesium sulfate, hydrogen chloride (hydrochloric acid), and calcium fluoride.

The identity of an element is determined by the number of protons. One cannot alter the number of protons without altering the identity of the element. By adding a proton, the atomic number increases by one and the element identity changes.

Number of neutrons can be altered to create isotopes. Number of electrons can be altered to create ions.