Atomic Structure & Periodic Table Flashcards

Which of the following describes the nucleus of an atom?

Answer: Small, positively charged, and very dense

The nucleus is tiny compared to the atom, contains protons and neutrons, and holds nearly all the atom's mass.

An element X is in Period 3, Group 6 of the periodic table. How many outer shell electrons does it have?

Answer: 6

The group number in the periodic table equals the number of electrons in the outermost shell.

Which statement about noble gases (Group 0) is correct?

Answer: They have a full outer electron shell

Noble gases have a full outer shell (8 electrons, or 2 for helium), making them very stable and unreactive.

Magnesium (atomic number 12) forms a 2+ ion. What is the electron configuration of Mg²⁺?

Answer: 2,8

Mg has configuration 2,8,2; losing 2 electrons gives Mg²⁺ a configuration of 2,8.

What evidence from the alpha particle scattering experiment led to the nuclear model of the atom?

Answer: A small number of alpha particles were deflected or bounced back

A small fraction bouncing back suggested a tiny, dense, positively charged nucleus that could repel the positive alpha particles.

As you descend Group 7 (halogens), the colour of the elements:

Answer: Gets darker

Fluorine is pale yellow, chlorine is green, bromine is red-brown, and iodine is dark grey/purple — progressively darker.

Which particle in an atom has negligible mass and a negative charge?

Answer: Electron

Electrons have a relative mass of approximately 1/1836 (essentially 0) and carry a charge of −1.