Periodic Trends - AP Chemistry

The atomic radii is the size of an atom when it is not bonded to any other atoms. The periodic table can be used to estimate the size of the atomic radii of atoms. As you move down the periodic table the atomic radii increase, but as you move from left to right on the periodic table, the size of the atomic radii decrease.

Beryllium, magnesium, calcium, strontium, and barium are all in the same group on the periodic table, so the smallest element is the element closest to the top of the periodic table since the atoms become larger as you go down the periodic table. Therefore, the smallest atom of this group is beryllium.

The noble gases possess a full octet of electrons. They have the largest first ionization energies because of their tendency to keep all of their valence electrons. Halogens have the highest electron affinity; therefore, they have high—but not the highest—ionization energies. The alkali and alkaline earth metals have low electron affinities and low ionization energies. Last, the metalloids possess ionization energies that are neither high nor low.

The metallic character of elements increases as you move down a group. All of the listed elements are in Group 5. Since is the furthest down, it must have the most metallic character.

When looking at a periodic table, you should notice that all of these elements are in the same period. Recall that atomic radii decrease as you move right on a period. Thus, this is the order of the elements by decreasing radius:

, or gallium, has the largest radius because it is the furthest left on the periodic table.

The correct answer is

has the most nonmetallic characteristics while has the most metallic characteristics. According to periodic trends, metallic character decreases from left to right across a period and increases top to bottom. Therefore, will show less metallic character than .

Electronegativity refers to the ability of an atom to attract and bind electrons. If the valence electrons are less then half full, then it takes less energy to lose an electron than gain electron making these atoms less electronegative. If the valence electrons are more than half full, then it takes less energy to gain electrons compared to losing an electron; therefore these electrons are more electronegative. The periodic table can be used to predict the electronegativity of the atom and how it compares to other atoms. As you move left to right of the periodic table, the electronegativity increases because the atoms on the right side of the periodic table have more valence electrons, and smaller radii. As you move down the periodic table the electronegativity decreases because the atomic number increases resulting in a greater distance between valence electrons and the nucleus causing less pull on the valence electrons.

Using the electronegativity periodic trend, we can predict which of the atom's is most electronegative. Aluminium, silicon, phosphorous, sulfur, and chlorine are all in the same row in the periodic table. Therefore, chlorine is the most electronegative because it is the farthest right on the periodic table so it has the most valence electrons and it will cost less energy to gain an electron than lose an electron.

Electronegativity refers to the ability of an atom to attract and bind electrons. If the valence electrons are less then half full, then it takes less energy to lose an electron than gain electron making these atoms less electronegative. If the valence electrons are more than half full, then it takes less energy to gain electrons compared to losing an electron; therefore these electrons are more electronegative. The periodic table can be used to predict the electronegativity of the atom and how it compares to other atoms. As you move left to right of the periodic table, the electronegativity increases because the atoms on the right side of the periodic table have more valence electrons. As you move down the periodic table the electronegativity decreases because the atomic number increases resulting in a greater distance between valence electrons and the nucleus causing less pull on the valence electrons.

Using the electronegativity periodic trend, we can predict which of the atom's is least electronegative. Oxygen, sulfur, selenium, tellurium, and polonium are all in the same group of the periodic table. Therefore, polonium is the least electronegative because it is closest to the bottom of the periodic table and has the largest atomic numbers. Since polonium has the largest atomic number, there is a greater distance between the valence electrons and the nucleus resulting in a decreased pull on the valence electrons. Therefore, it is easier to lose a valence electron compared to atom's with a smaller atomic number.

Atomic radius expands down the columns and to the LEFT.

Atomic radius INCREASES DOWN and TO THE LEFT in the periodic table

Electronegativity increases across a period (going right) and decreases down a group \[not including noble gases\]. The element closest to the top right is Phosphorous

Atomic radius increases down the columns and to the left. The furthest left elements are Na and Cs. Cs is furthest down so it is the biggest.

If we look at elements of the same period the prinicipal quantum number for each one of these elements is the same. Thus the outermost energy level for the electrons of each atom is the same. If we consider moving through the periodic table in numerical order, the left side of the periodic table features atoms that have just begun to add electrons to new energy levels. On the right side of the periodic table the elements are moving closer to filling the energy level. The differences in atomic radii are the result of differing amounts of protons between atoms whose electrons are in the same energy level. K has one electron in the fouth energy level and Kr has eight electrons in the fouth energy level. K has 19 protons with which to generate pull on the electrons. Kr has 36 protons with which to generate pull on the electrons. Thus Kr has a smaller atomic radius becasue of its ability to have a tighter grasp on its electrons becasue of the stronger charge generated by its nucleus.

Electronegativity measures the ability an atom to attract shared electrons
in bond. It follows a trend that it increases moving from left to right and down to up across
the periodic table.

The trend for radius is that it increases down and to the left

Atomic radius decreases as one moves across the periodic table from left to right, since effective nuclear charge increases and the electrons are held more tightly to the nucleus.

The alkali metals are found in the first group (column) of the periodic table, on the leftmost side. They have only 1 loosely bound electron in their outermost shells, and their effective nuclear charge values are low, giving them the largest atomic radii of all the elements in their periods.

The transition metals are capable of losing various numbers of electrons from the s and d orbitals of the valence shell. Metals such as Cu, Fe, and Mn have various oxidation states and can form many different ionic compounds.

Electronegativity increases as one moves across a period (row) from left to right, or up a group (column) from bottom to top. Following these trends, fluorine is the most electronegative element.

Effective nuclear charge increases as one moves across a period (row) from left to right, so Cl will have a higher effective nuclear charge. Anions of an element have a lower effective nuclear charge than their parent atom, since they have more electrons than protons and feel less of a pull from the protons in the nucleus. Thus, Cl will have the highest effective nuclear charge.