5. The Structure of Atoms

He found that passing electric current through some substances caused them to decompose, suggesting that the elements of a chemical compound are held together by electrical forces.

He determined the quantitative relationship between the amount of electricity used in electrolysis and the amount of chemical reactions occurring.

He suggested that the units of electrical charge associated with atoms be named electrons.

He performed the cathode-ray tube experiment and determined the ratio of the charge of the electron to its mass, which is 1.75882x10^8 Coulomb/gram.

He determined the charge of the electron through the famous "oil-drop experiment," in which he found that the charge of one electron was 1.60218x10^-19 Coulomb.

He observed that the cathode-ray tube also produced positively charged particles, created when gaseous atoms lose electrons. This led to the idea of a unit positive charge residing in the proton.

He discovered through the gold foil experiment that atoms consists of very small, very dense positively charged nuclei surrounded by clouds of electrons of relatively large distances from the nuclei.

The number of protons in the nucleus of an atom determines its identity; this number is known as the __.

These are atoms of the same element with different masses; they are atoms containing the same number of protons but different numbers of protons.

It is the sum of the number of protons and neutrons in the nucleus of an atom.

These are instruments that measure the charge-to-mass ratio of charged particles.

The Group 1A of the elements, except H, are called the __.

The Group 2A elements are called the __.

Group 7A elements are called __, which means "salt formers."

The Group 8A elements are called __.

__ character increases from top to bottom, and decreases from left to right. The opposite is the trend for __.

__ show some properties that are characteristic of both metals and nonmetals. Many of these elements are semiconductors.

Semiconductors are insulators at __ temperatures, but conductors at __ temperatures.

The conductivities of metals __ with __ temperature.

__ is the least metallic of the metals and is sometimes classified as a metalloid. It is metallic in appearance and an excellent conductor of electricity.

The __ is the distance between any two adjacent identical points of a wave.

The __ is the number of wave crests passing a given point per unit time.

Wavelength and frequency are __ proportional to each other.

It is a form of energy that consists of electric and magnetic fields that vary repetitively at right angles to each other.

It was __ that first recorded the separation of sunlight into its component colors by allowing it to pass through a glass prism.

It is a region in space which the probability of finding an electron is high.

Each of the possible states of electrons is described by four quantum numbers. We can use theses quantum numbers to designate electronic arrangements in all atoms, their so-called __.

This quantum number describes the main energy level, or shell, that an electron occupies. It may be any positive integer: 1, 2, 3, 4, ...

Within a shell, different sublevels or subshells are possible, each with a characteristic shape. This quantum number designates a sublevel, or specific shape of atomic orbital that an electron may occupy. This number may take integral values from 0 up to and including (n-1): 0, 1, 2, ... , (n-1)

This quantum number designates a specific orbital within a subshell. Within each subshell, it may take any integral values from -l through zero up to and including +l: (-l), ..., 0, ..., (+l)

This quantum number refers to the spin of an electron and the orientation of the magnetic field produced by this spin. For every set of quantum numbers (except this one), it can take the value of +1/2 or -1/2.

It corresponds to the electron configuration of an isolated atom in its lowest energy or unexcited state.

Each atom of an element is "built-up" by (1) progressively adding the appropriate number of protons and neutrons in the nucleus as specified by the atomic and mass numbers, and (2) adding the necessary number of electrons into orbitals in the way that gives the lowest total energy for the atom.

No two electrons in an atom may have identical sets of four quantum numbers.

Electrons occupy all the orbitals of a given subshell singly before paring begins. These unpaired electrons have parallel spins.

Substances that contain unpaired electrons are weakly attracted into magnetic fields and are said to be __.

Those which all electrons are paired are very weakly repelled by magnetic fields, and are called __.

__ is much stronger than paramagnetism, such that it allows a substance to become permanently magnetized when placed in a magnetic field. Only three free elements exhibit this.

It is an assembly of two protons and two neutrons.

These are two or more orbitals that have the same energy.