Chapter 2 Structure of the Atom

Formula for the maximum number of electrons in a shell

2n^2. n= shell number (K=1, L=2, M=3...) K shell: 2(1)^2=2 L shell: 2(2)^2=8 M shell: 2(3)^2=18

What is the max number of electrons the outside shell can hold?

8

Fundamental particles

A basic component of an atom, including the electron, neutron, and proton.

Alpha particles

A particle that has two protons bound to two neutrons, but no electrons. This particle has the same nucleus as a helium atom, but an alpha particle is not an atom because it has no electrons.

Period

A quality of elements in the Periodic Table of the Elements. Atoms in each period have the same number of electron shells. There are seven periods that correspond to the seven electron shells.

Dmitri Mendeleev

Advanced Dalton's work by organizing the known elements into the periodic table. It is arranged in order of increasing atomic mass with similar chemical properties.

isomer

Atoms that have the same number of protons and neutrons but a different binding energy.

Transitional metals

In the middle of the chart are a number of elements that do not easily fit into the eight groups. These elements are called the transitional metals in which inner electron shells are being filled.

What does the Greek word "atomos" means?

Invisible.

Ionization energy

The amount of energy required to remove an electron from an atom.

Niels Bohr's modern theory

-Bohr described the atom as being similar to our solar system. In the atom, electrons revolve around a nucleus in much the same way that planets revolve around the sun. -Center of atom made up of protons and nuetrons (nucleons). -Orbiting around the nucleus are electrons in defined energy levels and distances from the nucleus.

John Dalton

-Developed a sound atomic theory that is almost 200 years old. -All elements are composed of tiny indivisible and indestructible particles called atoms. -Compounds formed by molecules and molecules by fixed ratios of each type of constituent atom, resulting in a predictable mass. -Chemical reaction is an arrangement of atoms.

Joseph John "JJ" Thomson

-Discovery of the electron. -The glowing particles in the stream that passed through the cathode tube were negatively charged pieces of atoms. -atom=positively charged sphere with negatively charged electrons embedded into it.

Electron shell

-The orbit of an electron that surrounds the nucleus of an atom. -Energy levels around the nucleus. -Each shell is labeled with a letter beginning with K and continuing on with L, M, N, O, P and so on. -Each shell has a limit on the number of electrons it can hold. -K, the first shell, can only hold 2.

Elements

-simplest form of substance that produces matter. -each element is made up of one unique type of atom with an unchanging number of protons. -92 different elements in the natural world (oxygen, carbon, chlorine..) -almost 2 dozen have been created artificially.

Elements

-simplest forms of substances that compose matter -Each element is made up of only one unique type of atom with an unchanging number of protons. -The number of atoms that form a molecule of an element varies. -Ninety-two different elements exist in the natural world and more than a dozen others have been created artificially. -Familiar elements include oxygen, carbon, and chlorine.

Atom

Considered to be the basic building block of matter. It is made up of smaller particles called protons, neutrons, and electrons.

Electrical charge

Electrical charge is a characteristic of matter, whether it's a subatomic particle, an atom, or a large object. An electrical charge is not a thing itself; all kinds of matter have some form of electrical charge as part of their nature.

Ernest Rutherford

Gave us the nuclear model when his work described a "nucleus" surrounded by a cloud of electrons. -Stated that some particles can pass through the atom, some can't. -Established that they are mostly empty space.

Classification of the "isos"

Isotopes, isotones, isobars, isomers. The isos are a way of classifying elemental relationships based on the number of protons, neutrons, electrons in their constituent atoms.

Negative atom

More electrons. Negative ion or anion.

Positive atom

More protons. Positive ion or cation.

Neutron

One of the three fundamental units of an atom. A neutron has a neutral electrical charge

Proton

One of the three fundamental units of an atom. A proton has a positive electrical charge and is present in all atoms.

Electron

One of the three fundamental units of an atom. An electron orbits around the nucleus of an atom and has very little mass. It has a negative electrical charge.

Group

The elemental group is determined by the number of electrons in the outer most shell.

Inner transitional metals

The elements with the atomic numbers 57 to 71 and 89 to 103 are the inner transitional metals. They generally have special qualities; many are radioactive.

Binding energy

The energy that holds protons and neutrons together in the nucleus through the force of attraction; the amount of energy needed to break up the nucleus. The binding E is also a measure of the amount of energy needed to break up the atom.

Electron binding energy

The energy that keeps electrons in their shells. The electron binding energy of any one electron depends on how close the electron is to the nucleus and the total number of electrons in the atom. K has stronger binding than L because it is closer. Think of magnets and how it's harder to keep apart the closer they are together.

Strong nuclear force

The force of attraction between all the particles of a nucleus, both protons and neutrons.

Ionic bonding

The process in which an atom with a positive charge binds to an atom with a negative charge. Ionic bonding occurs when an electron from one atom transfers to another atom. The atom losing the electron becomes a positive ion, and the atom gaining the electron becomes a negative ion. Because opposites attract, the two ions are attracted and held to each other.

Element on the periodic table

The superscript number with the symbol is the atomic number (number of protons in the nucleus). The bottom number is the elemental mass (the characteristic mass of an element determined by the relative abundance of the constituent atoms and their respective masses). For example: "He" represents helium; the "2" is the atomic number and "4.0026" is the elemental mass.

Covalent bonding

Two atoms are bonded by sharing some of the same electrons which revolve around both nuclei. For example, a molecule of hydrogen is composed of two hydrogen atoms joined by a covalent bond. The two electrons, one for each atom, now revolve around both nuclei.

How were electrons discovered?

With the early cathode ray tube. An electron flow passing through certain gases was found to produce a glowing ray. That ray could be deflected by a magnet, showing that it contained charged particles that were affected by magnetic forces. These particles were known to have a negative electrical charge because they were attracted to the positive end of the cathode ray tube. Later experiments determined the mass of these particles, which were discovered to be much smaller than any atom.

chemical compounds

combinations of elements - water, hydrogen and one atom of oxygen.

pure form

not combined with other elements. iron, zinc, nickel, oxygen, carbon, hydrogen

Atomic mass number

number of protons and neutrons an atom has in its nucleus.

isobar

refers to elements whose atoms have a different number of protons, but the same number of protons and neutrons (atomic mass number).

isotone

refers to elements whose atoms have the same number of neutrons but different number of protons.

isotope

refers to the elements whose atoms have the same number of protons but a different number of neutrons.

Atomic number

refers to the number of protons the atom contains in its nucleus.

Molecule

two or more atoms bonded together form a molecule.