Understand basic chemistry - AP Biology

Two atoms are isoelectric if they each have the same number of electrons. Ions of an element will vary in the number of electrons, but isotopes will vary in the number of neutrons only. In its ground state, fluorine has 9 electrons, equal to the number of protons in order to have a neutral atom. Any ground state isotopes of fluorine will also have 9 electrons, making them isoelectric.

A nucleon is defined as a particle that is found in the nucleus of an atom. The nucleus is composed of proton particles and neutron particles. These are densely bound together to form a nucleus; thus, these two subatomic particles are nucleons.

Electrons are found in a wide radius outside the nucleus, and are not considered nucleons.

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.

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.

Intermolecular forces are transient forces between two separate molecules. Water is a polar molecule. The oxygen atom carries a slight positive charge, while the hydrogen atoms carry slight negative charges. This is the result of the large difference in electronegativity between oxygen and hydrogen. When two water molecules are next to each other, the partially positive hydrogen will be attracted to the partially negative oxygen. This attraction is known as a hydrogen bond.

Ionic bonds, covalent bonds, and double bonds are all _intra_molecular forces. These are stable bonds between atoms that establish the identity of the molecule. Breaking any of these bonds would alter the identity of the compound.

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 .

Because iron has multiple oxidation states, we need to follow the cation with the roman numeral that signifies how many electrons each iron ion has donated to oxygen. Since oxygen gains two electrons in order to satisfy its octet, the three oxygens will accept a total of six electrons from two iron atoms. This means that each iron must donate three electrons, so that each atom donates electrons equally. As a result, the name of the ionic compound is iron(III) oxide.

Another acceptable name for the compound would be ferric oxide. The term "ferric" refers to iron(III) and the term "ferrous" refers to iron (II).

Hydrogen bonding takes place when a hydrogen atom is attracted to a highly electronegative atom in another molecule. Hydrogen bonding takes place between hydrogen and either nitrogen, oxygen, or fluorine. Carbon has an electronegativity similar to hydrogen's, and will not hydrogen bond with hydrogens in other molecules.

Only molecules with -OH, -FH, or -NH groups can form hydrogen bonds.

Ionic bonds most commonly form between metals and non-metals. Non-metals have high electronegativities and metals have low electronegativities. In these type of bonds, electrons are transferred from the metal to the non-metal because of the large difference in electronegativities. The non-metal will try to gain an electron (high electronegativity) and the metal will try to donate an electron (low electronegativity). The result is a complete electron transfer, known as an ionic bond.

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: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:

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Electrons are notably smaller than nucleons (protons and neutrons), however, they have an equal amount of charge to protons. This is why an atom with the same amount of protons as electrons is considered electrically neutral.

The nucleus itself is positively charged, as the electrons are located relatively far away from the atomic center.

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.

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.

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.

Sulfate is a polyatomic ion that is composed of one sulfur atom and four oxygen atoms. The ion has a net charge of .

Since sodium ions have a charge of , we must use two atoms of sodium in order to result in a neutrally charged compound.

This makes the neutral chemical compound .