Chemistry Exam 1

Science

A way of knowing things about the world. Science is necessarily inductive, moving from observations to general principles

Hypothesis

A tentative exploration of observations. Can act as a guide for gathering & checking information

Law

A statement or equation that summarizes a large body of observations and can correctly predict further observations or outcomes

Theory

comprehensive, well-substantiated, thoroughly tested explanations of particular aspects of nature. Can be modified as new data is made available

Empedocles

Matter is composed of four elements

Democritus

Matter is made of “atoms” and “voids”

Cathode Ray Tube

Experiments by JJ Thompson with the Cathode Ray Tube led to the discovery of the electron. JJ Thompson is credited with the discovery of the electron.

John Dalton

John Dalton’s atomic theory gave some advanced and mostly accurate theories on atoms, like that atoms are neither created or destroyed during chemical reactions. He also came up with the Law of Multiple Proportions.

The Law of Multiple Proportions

John Dalton. Elements can combine in multiple sets of proportions; each proportion corresponds to a unique compound.

Plum Pudding Model

JJ Thompson; negatively charged particles in a positively charged mush

Robert Millikan

Via oil drop experiment, Millikan discovers the charge on an electron

Ernest Rutherford

Via gold foil experiment, Rutherford discovers the proton and nucleus

Bohr Model

Electrons move in fixed orbits around the nucleus

Quantum Mechanical model

Formed in 1920s by Erwin Schrödinger. Electrons have particle-like and wave-like properties. There is a region of space around a nucleus where an electron has a probability of existing (orbital).

Periodic Table: vertical columns

Families/groups

Periodic table: Rows

Periods/rows

Periodic Table: Group 1

Alkali Metals

Periodic Table: Group 2

Alkali Earth Metals

Periodic Table: Group 17

Halogens

Periodic Table: Group 18

Noble Gases

What determines the element?

Protons

What determines the mass of an element?

The average of the mass of different isotopes

What is an ion?

An atom or molecule that has lost or gained electrons, giving it an electrical charge.

Anion

An ion with a negative charge (gains electrons)

Cation

An ion with a positive charge (loses electrons)

What is an isotope?

Atoms with the same identity but a different number of neutrons

Mass spectrometer

Measures the mass of atoms and molecules

Blackbody radiation and the ultraviolet catastrophe

Energy is quantized

Atomic spectra

Electron energies are quantized

The photoelectric effect and the double slit experiment

Light is both a particle and a wave

Quantized

When something can only take on select values

Continuous

When something can take on any arbitrary value

Double-slit experiment

Led scientists to conclude that light is both a particle and a wave. The electron appears both places at once; it is an example of paradox and faith win science

Clinton Davisson and Lester Germer

Demonstrated the diffraction of electrons by a nickel crystal. The presence of diffraction indicates that they are behaving as waves.

T or F? Electrons in atoms can absorb or emit light of a defined wavelength to increase or decrease their energy, respectively

T

Where do orbitals and their energies come from?

The shapes of the orbitals, and the energy an electron has in any orbital, are both results of solving the Schrödinger equation for a given atom

Light as a wave:

Oscillating wave with both electric field and magnetic field components

Light as a particle:

1 photon = energy of hv

Rules for naming molecular compounds:

1. Identify the first element by its name

2. name the second element and change its ending to -ide

3. use prefixes to indicate the number of each element in the compound

Rules for naming ionic compounds:

1. write the metallic element first

2. then the root of the nonmetallic element with the suffix -ide

Why do molecules have their shapes?

A molecule will adopt the structure that minimizes its potential energy

Four types of “electron sets” or “electron groups”

1. lone pairs

2. single bonds

3. double bonds

4. triple bonds

Electron geometry:

The overall shapes of the molecule, including all 4 types of “electron sets” from the first page

Molecular geometry:

Also describes the shape of the molecule, but only refers to the placement of atoms, not lone pairs of electrons

The electromagnetic spectrum:

Energy and wavelength are inversely proportional

Wavelength and frequency are inversely proportional

Ionic bonds:

1. Electrons are taken or donated

2. Species in compound are charged 

3. From from far left and far right of the periodic table (metal and non-metal)

Often, ionic compounds contain a polyatomic ion: a covalent molecule that has an overall charge 

Tend to: 

• Have very high boiling and melting points 

• Be hard but brittle 

• Conduct electricity when dissolved

Covalent bonds:

1. Elections are shared 

2. Nonmetals bonded together 

3. Polymers: carbon-based covalent compound chains 

Tend to:

• Have lower melting and boiling points 

• Be not as hard and less brittle 

• Have lower solubility in water 

• Not conduct electricity when dissolved