not exactly physical science, but I'm confused about how you tell the charge of elements in the B groups on the periodic table
B groups? Your periodic table is out of date by 30 years. Let me go find one with B groups.
http://en.wikipedia.org/wiki/Group_(periodic_table)
OK, there are two outdated periodic tables, each of which use B for something different. I suspect from your question you are asking about the valence of the transition elements, in which the outer electrons occupy the d level energy. There is no way to know the valence the elements will form except memory, most can have several valence states, due to the interaction of the d and s levels. Manganese is a favorite of mine, examine its common valence states.
Is is possible your instructor can start teaching the new periodic table, something the rest of the world has used since 1980, having eighteen families. See
http://en.wikipedia.org/wiki/Group_(periodic_table)
And your question is a little confusing, too. ALL elements in the periodic table have a charge of zero when they are in their elemental state. You may be asking how to tell the charge on the ions. For the B group of elements, ONE of the possible ionic charges (valence) is always the number of the group (same as the A families). There may be other possible valences in their compounds, too, and those you need to either memorize OR look at the electron configuration. SOMETIMES, the electron configuration will help you decide if another valence is possible.
Example 1. Cu is in group IB and ONE of its valences is + 1 and there are a number of compounds in which Cu displays a valence of +1. Cu also has a valence of +2 and that is its more common valence. Au in group IB also has a valence of +1 but it also has a valence of +3. I don't know how to do those except by memory.
Example 2: Mn in group VIIB has a possible valence of +7. It ALSO has common valences of +2, +4, less common is +6 and some others. For Mn (element #25) the electron configuration is
1s2 2s2 2p6 3s2 3p6 3d5 4s2.
The +2 valence can be seen easily by simply removing the 2 4s2 electrons. The +7 is easily seen by removing all 3d and 4s electrons (7 total). The other valences aren't so easily predicted from this venue. I hope this helps. Let me know if this isn't close to what you were looking for or if you need further explanation.
Determining the charges of elements in the B groups, also known as transition metals, on the periodic table can be a bit more complicated compared to the elements in A groups (Groups 1 and 2) or nonmetals. However, there are a few patterns and general guidelines that can help you understand and predict their charges.
1. Understand the concept of oxidation states: The charge of an element in a compound is often referred to as its oxidation state. Oxidation states indicate the number of electrons that an atom has gained or lost in order to achieve a stable electron configuration.
2. Determine the common oxidation states: For many transition metals, there are common oxidation states that they commonly exhibit. These common oxidation states are often listed in parentheses in the periodic table. For example, iron (Fe) can have oxidation states of +2 and +3, copper (Cu) can have +1 and +2, and so on.
3. Consider the electron configuration: Transition metals have a variable number of valence electrons, which contributes to their ability to exhibit multiple oxidation states. By looking at the electron configuration, you can determine the possible oxidation states. For example, iron (Fe) has an electron configuration of [Ar] 3d⁶ 4s². In order to achieve a stable configuration, it can either gain two electrons (Fe²⁺) or lose three electrons (Fe³⁺).
4. Observe periodic trends: You can observe certain periodic trends to help predict oxidation states of transition metals. Generally, as you move across a period from left to right, the oxidation states of transition metals tend to increase. On the other hand, as you move down a group, the oxidation states can become more varied and include higher charges.
5. Consult reference materials: If you're unsure about the specific charges of a transition metal, you can refer to reliable sources such as textbooks, chemistry databases, or reputable websites that provide information on the properties and characteristics of elements.
It is important to note that transition metals can exhibit different oxidation states depending on the chemical reaction they participate in or the compounds they form. The above guidelines provide a starting point, but it is always best to consult reliable sources for specific information about each transition metal.