Have each group member choose a row of the transition metals in the periodic table and ask each to look up and graph (where appropriate) a trend, choosing from the following: electron configuration, atomic size, ionization energy, or electronegativity. Present your graph to the group. Describe the general trend and any notable exceptions. If possible, form new groups with individuals who researched the same property for a different row of the periodic table.

The electron configuration of an atom provides a foundation for understanding the chemical behavior of elements, especially transition metals. Transition metals are elements with partially filled d-orbitals, which fall between Groups 3 to 12 in the periodic table.

As we move across the period from left to right within the transition metals, the d-orbitals become progressively filled. This process follows the Aufbau principle, where electrons fill orbitals starting from the lowest energy level to higher energy levels. For instance, the electron configuration of Scandium (Sc) starts with the d-orbital being filled with one electron, and by the time we reach Zinc (Zn), the d-orbital contains ten electrons.

Notably, the shape and energy of the d-orbitals allow transition metals to exhibit a variety of oxidation states and coordination compounds, leading to their wide use in industrial catalysis and the coloration of gemstones. The presence of these d-electrons affects many properties, such as the magnetic character of these metals and their ability to participate in intricate chemical reactions.

The term 'atomic size' refers to the distance between the nucleus of an atom and the outermost electrons. When discussing transition metals, the atomic size generally decreases from left to right across a period, but this trend is not as uniform as with other elements.

This slight decrease in size is due to what's known as the 'effective nuclear charge.' As protons are added to the nucleus, they pull on the electron cloud with greater force. However, because the additional electrons are being added to the same d-orbital, the shielding effect remains relatively constant, causing the atomic radius to shrink only slightly.

It is important to understand this concept because the size of an atom can influence its reactivity and the types of bonds it forms. Typically, a smaller atomic size among transition metals can lead to higher densities and higher melting points, which are characteristic of these elements.

Ionization energy is the energy required to remove an electron from an atom in the gas phase. For transition metals, ionization energy generally increases as you move from left to right across a period.

This increase is due to the stronger hold the nucleus has on the electrons as atomic number, and thus nuclear charge, increases. Transition metals, with their d-electrons, have a more complex interaction between these electrons and the nucleus compared to s and p block elements. This means that while the trend in increasing ionization energy is observed, the increments can be less pronounced.

Understanding ionization energy is pivotal when predicting the chemical reactivity of an element, as elements with lower ionization energy are typically more reactive. This is because they tend to lose electrons more readily, which is a key factor in chemical reactions.

Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. In the case of transition metals, electronegativity typically increases across a period, albeit not in a uniform pattern.

The slight increase in electronegativity across the transition series can be attributed to the increasing positive charge of the nucleus, which more effectively attracts bonding electrons. However, the additional electrons are being added to the same energy level and d-orbital, resulting in a poorer shielding effect; this causes the increase in electronegativity to be less dramatic than in other elements.

Electronegativity is a vital concept in chemistry as it helps predict the type of bonding that will occur between atoms and the polarity of the resulting molecules. In transition metals, varying electronegativity allows them to form complex ions with both ionic and covalent character, which is fundamental to understanding their role in many biological and industrial processes.