Structure of Matter

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Structure of Matter 저자: Mind Map: Structure of Matter

1. Ionization

1.1. Electron Shells

1.1.1. Electrons are held in orbit by an electrostatic centripetal force

1.1.2. Each shell has a specific electron binding energy, or Eb The closer the shell is to the nucleus, the stronger the Eb Larger and more complex atoms will have a stronger Eb

1.1.3. The maximum # of electrons in a given shell is defined as 2n^2 where n is the shell #

1.1.4. Contributes to chemical nature of the atom How it combines with other atoms

1.1.5. No outer (or valence) shell can contain more than 8 electrons

1.1.6. Shells are named starting with K, so K=1, L=2, and so on

1.2. Ionization is the removal of an orbital electron from an atom

1.2.1. The energy required to remove an electron from its shell must be equal to, or greater than, the Eb

1.2.2. A change to the # of protons does NOT make an atom ionized - it makes a different atom

1.2.3. The resulting ionized atom and released electron are called an ion pair

2. Elements

2.1. The Periodic Table lists matter in order of increasing complexity

2.1.1. Hydrogen is the most simple with one proton in its nucleus and one electron

2.1.2. Uranium 238 is the most complex naturally occurring element with 92 protons and 146 neutrons

2.2. Elements are also grouped into eight columns based on the number of electrons in the valence shell (since eight is the maximum # of outer shell electrons)

2.2.1. Elements with the same number of outer shell electrons reveal how the atom will react chemically

2.2.2. Elements in the 4th group are called the "transitional elements"

2.3. Elements are commonly referred to by an alphabetic abbreviation

2.3.1. The total number of protons is called the atomic number, represented by Z, and is written as a subscript to the chemical symbol

2.3.2. The total number of protons and neutrons is called the atomic mass number, represented by A, and is written as a subscript to the chemical symbol The atomic mass number (A) is not the precise mass of an atom. The exception is 12C (carbon 12) as it is the arbitrary standard for atomic measure.

2.3.3. Tungsten The atomic mass number (A) is written as superscript The atomic number (Z) is written as subscript The atomic number (Z) is often omitted as the element also indicates the atomic number

3. Radioactivity

3.1. Radioactivity is the emission of particles and energy in order to become stable

3.2. Radioactive decay results in emission of alpha particles, beta particles, and usually gamma rays

3.2.1. During beta transmission, an electron created in the nucleus is ejected with great kinetic energy. Simultaneously, a neutron converts to a proton. The atomic mass (A) stays the same, but the atomic number (Z) in creases by one, changing the atom to a different element.

3.2.2. Alpha emission is a much more violent form of radioactivity and the nucleus must be extremely unstable. An alpha particle consisting of two protons and two neutrons (atomic mass of 4) is ejected. The resulting atom is chemically changed by the loss in atomic number (Z) of two and atomic mass (A) of 4.

3.3. The half-life of a radioisotope is the time required for a quantity of radioactivity to be reduced to one-half its original value

3.4. All ionizing radiation can be classified as either particulate of electromagnetic

3.4.1. Particulate radiation includes alpha and beta particles An alpha particle is the equivalent of a helium nucleus - two protons and two neutrons Higher energy - shorter range A beta particle is an electron emitted from the nucleus of a radioactive atom Lower energy - longer range The only difference between a beta particle and an electron is the source

3.4.2. Electromagnetic radiation includes gamma rays and x-rays. The only difference between gamma rays and x-rays is the source Gamma rays are produced from the nucleus of a radioisotope X-rays are produced in the electron shells Called photons, both have no mass, no charge, travel at the speed of light, and a similar ionization rate to beta particles. The range is unlimited, but loses intensity with distance.

4. Atomic Configurations

4.1. Isotopes

4.1.1. Atoms of the same element that have a different # of neutrons

4.1.2. Have the same atomic # but different atomic mass #s

4.1.3. Isotope of the same element chemically react the same way

4.1.4. Many chemically stable isotopes exist in nature

4.2. Isobars

4.2.1. Have different #s of protons & neutrons, but the same # of nucleons

4.2.2. Atomic nuclei that have the same atomic mass # but different atomic #s

4.2.3. When radioactive elements decay, the daughter atom is a different element than the parent atom

4.3. Isotones

4.3.1. Atoms that have the same # of neutrons but different #s of protons

4.3.2. Different atomic # (Z) & different atomic mass (A)

4.4. Isomers

4.4.1. Atoms with the same atomic # (Z) & same atomic mass (A), but exist at different energy levels

4.4.2. Isomers are identical atoms. They have different energy levels because of differences in nucleon arrangement.

5. Structure of an Atom

5.1. Fundamental Particles

5.1.1. Electons Located in shells orbiting the nucleus Have a negative charge Symbolized by e-, or just -

5.1.2. Nucleons Protons Have a positive charge Determines the chemical element Symbolized by + Neutron Electrically neutral Similar in weight to a proton Symbolized by O Both have an atomic mass number of 1

5.2. Subatomic Particles

5.2.1. Quarks Make up the structure of the nucleons

5.2.2. Gluons Hold the nucleons together

5.2.3. > 100 others theorized to exist

5.3. The atom is essentially empty space

5.3.1. The nucleus contains > 99.998% of an atom's mass

5.3.2. If a basketball represented the size of an uranium nucleus, the path of the orbiting electrons would have a 16 mile diameter!

5.4. In their normal state, atoms are electrically neutral.

5.5. The most commonly used model of the atom is the Bohr atom - the atom resembles a miniature solar system

6. Molecules

6.1. Atoms of various elements may combine to form structures called molecules

6.1.1. Covalent bonds: the atoms share an electron Very strong, such as water (H2O)

6.1.2. Ionic bonds: one atom will give up an electron to another atom. The two will be attracted to each other magnetically. Not as strong. Salt, for instance (NaCl) is easily disolved in water.

6.2. A chemical compound is any quantity of one type of molecule

6.2.1. The shorthand notation of a molecule incorporates the chemical symbol with subscripts and two superscripts Example: Sodium, hydrogen, carbon, and oxygen atoms can combine to form baking soda: NaHCO3

6.3. The smallest particle of an element is an atom; the smallest particle of a compound is a molecule