Introduction to Periodic Table Groups and Periods

The periodic table is organized into elements based on vertical and horizontal arrangements known as groups and periods.
Vertical Lines (Groups): - The vertical columns in the periodic table are called groups. - Specific group designations mentioned include Group $1A$ , Group $8A$ , and Groups $3B$ through $2B$ . - The groups spanning from $3$ to $12$ are specifically identified as part of these designations. - In total, the periodic table contains groups numbered up to $18$ .
Horizontal Rows (Periods): - The horizontal rows in the periodic table are referred to as periods. - There are exactly $7$ periods in the periodic table. - Although there are rows placed underneath the main body of the periodic table, these elements actually belong within the existing rows on top. - Because these separate rows belong within the others, they do not count as extra rows; the total count remains $7$ . - The periods are numbered sequentially from $1$ to $7$ starting from the top of the table.

Grouping Rationale: Elements are categorized into specific groups because they share "same or very similar chemical properties."
Chemical Families: Elements within the same group are considered a "family."
Behavioral Patterns: - Like human families, chemical families have things in common. - Family members "act alike" even if they do not necessarily "look alike." - This means that while elements in a group might not share common physical properties, they react in similar ways. - For instance, Group $1$ is a family, Group $2$ is a family, and this continues through Group $18$ .

Reactivity of Group 1: If one element in a group exhibits a specific reactive behavior, it can be assumed that other elements in that same group will exhibit similar behavior.
Example: Sodium ( $Na$ ): - Sodium reacts "violently" with water. - If sodium is placed near or in contact with water, it will explode.
Distinction Between Element and Compound: - It is critical to distinguish between elemental sodium and sodium compounds found in daily life. - Sodium Chloride ( $NaCl$ ): This is common table salt consumed in food. - Medical Context: When a doctor advises a patient with high blood pressure to "watch your sodium," they are referring to the consumption of sodium chloride ( $NaCl$ ), not the pure metal element sodium.
Predictive Reactivity: - Knowing the behavior of sodium allows for predictions about its group members. - One can assume that other elements in Group $1$ will also react violently with water. - While the intensity of the reaction will differ (some may react more violently than others), the fundamental nature of the violent reaction remains consistent across the group.

Question: How many rows (periods) do you have in the periodic table?
Response: There are $7$ rows. Although elements are listed underneath, they belong with the ones on top, so it is not two extra rows; it is only $7$ in total.
Question: If sodium reacts violently with water, can we assume other elements in that same group also react violently?
Response: Yes. The degree of violence in the reaction will differ between elements, but they will all react violently with water.