Chapter 1: Atomic Structure

Question 1

What is an ion?

Answer 1

An ion is an atom that gains or loses electron/s, becoming charged.

Question 2

What is the atomic number of an atom?

Answer 2

The number of protons in the nucleus of the atom.

Question 3

What is the mass number of an atom?

Answer 3

The number of protons and neutrons in the nucleus of the atom added together.

Question 4

What is an isotope? How do isotopes differ?

Answer 4

An isotope is a version of an element with a different number of neutrons.
Isotopes have similar chemical properties but different physical properties due to their different masses.

Question 5

What do the coloured lines on an emission spectrum for an element represent?

Answer 5

Each line represents a specific energy level in the spectrum.

Question 6

List the atom and it’s components in the order of when they were discovered, ranging from first to last.

Answer 6

Atom > Electron > Proton, Nucleus > Neutron

Question 7

What is the relative mass of an electron?

Answer 7

1/1837.

Question 8

What did English scientist Sir J.J. Thomson’s model of the atom show?

Answer 8

The ‘plum pudding’ model proposed that atoms were positively charged spheres with negatively charged particles called electrons embedded in them.
It also showed that atoms were not indivisible.

Question 9

What was Ernest Rutherford’s flaw in his proposal of the atom?

Answer 9

Rutherford’s model proposed that the orbiting electrons would eventually lose energy and spiral in towards the nucleus.

Question 10

Describe Niels Bohr’s model of the atom.

Answer 10

Bohr suggested that the electrons surrounding the nucleus were on fixed energy levels called shells. The electrons would orbit around the nucleus on these shells.

Question 11

What did Sir James Chadwick discover about the atom?

Answer 11

Chadwick discovered that the nucleus contained both protons AND neutrons, uncharged particles with relatively same mass.

Question 12

What was Bohr’s explanation for the atomic emission spectra of elements?

Answer 12

Bohr suggested that when given excess energy, electrons jump up to higher energy levels, from ‘ground state’ (lowest energy level) to an ‘excited state’.
When returning to their original ground state, the excess energy is emitted as a photon (quantum of light), producing a colour on the spectrum.

Question 13

What are electron shells?

Answer 13

Electron shells are regions of space surrounding the nucleus, and there is a definite energy level associated with each. They are numbered 1, 2, 3, 4… and ordered K, L, M, N… starting from the innermost shell.

Question 14

How many electrons can each shell hold?

Answer 14

The maximum number of electrons a shell can hold is 2n^2, where n is the shell number. However, for the first 20 elements the outer shell never has more than 8 electrons.

Question 15

What are valence electrons, and what do they influence?

Answer 15

Valence electrons are those in the highest energy level of an atom. They mainly determine the chemical properties of elements.

Question 16

What are subshells? How many in each shell?

Answer 16

Subshells are are different energy levels found in shells. The number of subshells equals the shell number. They are represented by the letters s, p, d, f…

Question 17

What could Bohr’s model of the atom not explain?

Answer 17

Bohr’s model could not explain why electrons emitting electromagnetic radiation did not fall into the nucleus of the atom, causing it to collapse.
It could also not explain or predict the emission spectra of the more complex atoms, only hydrogen.

Question 18

How is the group number found?

Answer 18

The group number is the number of valence electrons in the outermost shell.

Question 19

How is the period found?

Answer 19

The period is the amount of shells the atom has.

Question 20

What are the two exceptions to the typical electron configuration pattern?

Answer 20

Chromium, Cr, and copper, Cu, partially fill their 4s subshell in order to give their 3d subshell a more stable arrangement.

Question 21

What are orbitals?

Answer 21

Orbitals are regions of space, consisting of various shapes, and are found in subshells, which in turn are found in shells. Each orbital can hold 2 electrons, but are only able to hold a second when all other orbitals in the subshell are half filled.