Atomic Structure and Chemical Composition

A chemical bond formed when two atoms share a pair of electrons.

A compound formed by the sharing of electrons between two nonmetals.

A chemical formula that represents the simplest ratio of atoms in a compound.

A chemical formula that represents the actual number of atoms of each element in a molecule.

A type of covalent bond where electrons are shared unequally between atoms.

A type of covalent bond where electrons are shared equally between atoms.

A property of a molecule that has opposite partial charges due to an uneven distribution of electrons.

The ability of a molecule to attract and hold onto electrons.

The nucleus of an atom is the central core and contains both protons and neutrons.

Potassium is a metal, while chlorine is a non-metal.

Aluminum (Al) has a +3 charge and sulfur (S) has a -2 charge. To form a neutral compound, you need two aluminum atoms for every three sulfur atoms.

The correct name for SrO is strontium oxide.

PCl3 is named phosphorous trichloride.

The formula for ammonium carbonate is (NH4)2CO3.

The name of this compound is chromium (III) chloride.

An electron is the smallest and lightest subatomic particle.

The set of three quantum numbers (n, l, ml) that describes a 3d orbital is (3, 2, -2). The principal quantum number (n) indicates the energy level, the angular momentum quantum number (l) indicates the shape of the orbital, and the magnetic quantum number (ml) indicates the orientation of the orbital in space. For a d orbital l=2 and ml = -2, -1, 0, 1, 2.

The maximum number of electrons each subshell can hold depends on its shape. The s-subshell has a spherical shape and can hold a maximum of 2 electrons. The p-subshell has a dumbbell shape and can hold a maximum of 6 electrons. The d-subshell has a complex shape and can hold a maximum of 10 electrons.

The modern periodic table arranges elements in order of increasing atomic number. This means that the number of protons in the nucleus of these elements increases as you move across the periodic table.

Elements within the same group (column) of the periodic table are classified as a chemical family and display similar chemical properties due to having the same number of valence electrons. The number of valence electrons determines an element's reactivity, and how it bonds with other elements.

The atomic radius generally increases down a group due to increasing principle quantum number (n) of the valence orbitals. As n increases, the average distance from the nucleus to valence electrons also increases.

Atomic radius is the size of an atom. Atoms have a smaller radius when they have a higher nuclear charge, meaning a stronger attraction between the nucleus and electrons. Atoms with higher nuclear charge pull electrons in closer, leading to a smaller radius.

Isoelectronic species have the same number of electrons. In this case, O2-, F-, Ne, and Na+ all have 10 electrons. Elements are arranged in order of increasing nuclear charge for an isoelectronic series of elements.

Atomic radius increases moving down a group and decreases moving across a period. The order of increasing atomic radius is F < Br < Ge < Rb < K. Fluorine (F) is the smallest atom. Rubidium (Rb) is the largest atom.

The element with the highest ionization energy in the given list is Fluorine (F) . Ionization energy is the energy required to remove one electron from a neutral gaseous atom . Fluorine has the highest ionization energy because it has the smallest atomic radius and the strongest attraction between the nucleus and outermost electron . The smaller atomic radius ( due to strong nuclear pull ) , the higher the ionization energy .

The second ionization energy is the energy needed to remove the second electron from a singly charged ion ( after the first electron was removed ) . Magnesium ( Mg ) has the largest second ionization energy in the list due to its electronic configuration . After losing one electron, Mg+ becomes isoelectronic with Na . To remove the second electron, we need to break into a stable noble gas core configuration .

The first ionization of aluminum is represented by the equation Al(g) Al + (g)  e- , where a neutral gaseous aluminum atom loses an electron to become a positively charged gaseous ion .

The ion with the largest radius is Br- . Larger anions have larger radii . The Br- ion has more electron shells ( energy levels ) than other species so it should have a larger radius .

Oxygen (O) has the highest electronegativity in the list. Electronegativity is the ability of an atom to attract the electron pair in a covalent bond . Oxygen has a higher electronegativity due to its small atomic radius and high nuclear charge .

Metallic character increases down a column of the periodic table, as the atomic size increases and the outermost electron is held less tightly by the nucleus. Thus, Na > K > Rb.

Bromine (Br) will most likely form a Br- ion based on the octet rule ( which states that atoms tend to gain, lose, or share electrons in order to achieve a stable outer shell of 8 electrons ) . Bromine requires one more electron to achieve a noble gas electron configuration .

Strontium (Sr) will most likely form a Sr2+ ion based on the octet rule . Strontium, having two valence electrons, loses them to attain a noble gas configuration.