Question

cer: periodic table & atomic structure. an unknown element is discovered and placed in group 2 and period 4 of the periodic table. a student claims that this element has similar numbers of electrons in its outer shell as other elements in group 2, and that it contains 20 protons. do you agree or disagree with the students claim? use what you know about the periodic table and atomic structure - specifically the number of protons, neutrons, and electrons - to support your answer. claim, evidence, reasoning

Explanation:

Step1: Recall periodic - table facts

Elements in Group 2 have 2 outer - shell electrons. The atomic number (number of protons) determines the element's position in the periodic table.

Step2: Analyze the claim

If an element has 20 protons, its atomic number is 20. Calcium (Ca) has an atomic number of 20. Elements in Group 2 and Period 4 should have 2 outer - shell electrons and an atomic number such that it fits in that position. Calcium has 2 outer - shell electrons as it is in Group 2.

Step3: Provide evidence

The number of protons (20) for the unknown element places it as calcium in the periodic table. Elements in Group 2 have a characteristic electron - configuration with 2 outer - shell electrons. Calcium's electron - configuration is 2, 8, 8, 2, which shows 2 outer - shell electrons.

Step4: Reasoning

Based on the periodic - table organization and atomic - structure knowledge, the claim is reasonable. Elements in the same group have similar chemical properties due to the same number of outer - shell electrons. Since the unknown element has 2 outer - shell electrons like other Group 2 elements and has 20 protons placing it in Period 4, the claim is valid.

Answer:

Claim: The student's claim is valid.
Evidence: The element with 20 protons is calcium. Elements in Group 2 have 2 outer - shell electrons, and calcium has an electron - configuration of 2, 8, 8, 2 indicating 2 outer - shell electrons.
Reasoning: The periodic table organizes elements based on atomic number (number of protons) and electron - configuration. Elements in the same group have similar outer - shell electron numbers and similar chemical properties.