Which of these patterns of the periodic table is not correct?
A. Atomic size increases down a group and across a period.
B. Densities and melting points increase down any group.
C. In metallic groups, reactivity increases down a group.
D. In non-metallic groups, reactivity decreases down a group.
Answer:A
Which of these patterns of the periodic table is not correct?
A. Atomic size increases down a group and across a period. B. Densities and melting points increase down any group. C. In metallic groups, reactivity increases down a group. D. In non-metallic groups, reactivity decreases down a group.
Explanation: The atomic size or radius does increase down a group, but it decreases across a period. This is because, as protons are added to the nucleus, the electrons are pulled closer to the nucleus, which decreases the atomic radius.