Unit 1: Atomic Structure and Properties

Flashcards covering AP Chemistry Unit 1: Atomic Structure and Properties, including historical models, subatomic particles, mass spectroscopy, chemical laws, PES, and periodic trends.

What percentage of the AP Exam does Unit 1 (Atomic Structure and Properties) cover?

7-9%

Which scientist performed the Gold foil experiment and proposed the Planetary Model?

Rutherford

Identify the model associated with J.J. Thomson and his work with cathode ray tubes.

Plum-Pudding Model

According to the transcript, how is an Atomic Mass Unit (AMU) defined?

$1/12$ of a carbon-12 atom

What is the specific value of a mole in terms of particles?

$6.022 \times 10^{23}$ particles

What is the formula provided for calculating Average Atomic Mass?

$(mass_1 \cdot \%_1) + (mass_2 \cdot \%_2) + \dots$ (where percentages are expressed as decimals)

In mass spectroscopy, what do the relative size of the peaks indicate?

The relative number of the particle (relative abundance)

What does the Law of Definite Proportions state?

The ratio of the masses of the elements in any pure sample of that compound is always the same (simple whole number ratios).

What constitutes a pure substance versus a mixture?

Pure substances consist of elements and compounds; mixtures can be homogeneous or heterogeneous.

What is the formula for Percent Composition?

$$\text{\%} = \frac{(\text{mass of element})}{\text{total mass}} \times 100$$

Specify the relationship expressed in Coulomb’s Law according to the notes.

$$F_{\text{coulombic}} \propto \frac{q_1q_2}{r^2}$$

In a PES (Photoelectron Spectroscopy) diagram, what does a higher energy peak indicate regarding electron location?

The electrons are closer to the nucleus.

Define Hund's Rule regarding the arrangement of electrons.

The most stable arrangement has the maximum number of unpaired electrons; one electron enters each orbital before doubling up, and all single electrons have parallel spins.

Define the Pauli Exclusion Principle.

No two electrons can have the same quantum numbers; there are two electrons per orbital, and they must have opposite spins.

What are the special names for Group 16 and Group 17 on the periodic table?

Group 16: Chalcogens; Group 17: Halogens

What is the periodic trend for Atomic Radius and why?

It increases down (increasing energy level) and to the left (decreasing effective nuclear charge).

What are the two notable exceptions to the Ionization Energy trend mentioned in the transcript?

Between group 2 and group 13 (difference in s and p orbitals) and between group 15 and group 16 (difference in paired and unpaired electrons/electron-electron repulsion).

Compare the size of cations and anions to their respective neutral atoms.

Cations are smaller than their atom (less electron-electron repulsion); anions are larger than their atom (more electron-electron repulsion).

What does the term 'isoelectric' mean?

Species having the same number of electrons.

Define Electronegativity and its periodic trend.

The ability of an atom in a molecule to attract electrons to itself; it increases up and to the right.

What is the difference between valence electrons and core electrons?

Valence electrons are in the outermost energy level; core electrons are not in the outermost energy level.