Question

patterns in properties
the term periodic meansrepeating pattern. for example, seasons and
months are periodic because they follow a repeating pattern every year. the
days of the week are periodic since they repeat every seven days.
what were some of the repeating patterns mendeleev noticed in his table?
melting point is one property that shows a repeating pattern. recall that
melting point is the temperature at which a solid changes to a liquid. the blue
line in the figure below represents the melting points of the elements in row 2
of the periodic table. notice that the melting point of carbon is higher than the
melting point of lithium. however, the melting point of fluorine, at the far right
of the row, is lower than that of carbon.
how do these melting points show a pattern? look at the red line in the figure.
this line represents the melting points of the elements in row 3 of the periodic
table. the melting points follow the same increasing and then decreasing
pattern as the blue line, or row 2. boiling point and reactivity also follow a
periodic pattern.

row 2
row 3

infer what pattern do you see in the melting points of rows 2 (blue line) and 3 (red
line) in the periodic table on the graph?

Explanation:

The text describes that the melting points of elements in row 2 (blue line) and row 3 (red line) of the periodic table follow a pattern where they first increase and then decrease. This is a characteristic periodic pattern as seen in the graph provided.

Answer:

The melting points of elements in rows 2 and 3 of the periodic table show a pattern of first increasing and then decreasing.