Chapter 1: Atoms, Ions, Isotopes, Molecules, and Ionic solids Flashcards
Scientific Notation
Scientific notation is a convenient way to handle really large or really small numbers.
Ex.
1.0 x 10^6 = 1,000,000 (million 6 zeros)
1.0 x 10^9 = 1,000,000,000 (billion 9 zeros)
1.0 x 10^-6 = .000,000,1 (millionth 6 zeros)
1.0 x 10^-9 = .000,000,000,1 (billionth 9 zeros)
Atom
All mater is composed of atoms; all atoms are composed of 3 subatomic particles neutrons (no electrical charge), protons (positive electrical charge), and electrons (negative electrical charge); the electrons of an atom surround a small very dense nucleus composed of protons and neutrons; all atoms are neutral protons = electrons
Mass
The weight of an object on earth
Inertia
An objects ability to resist movement. The greater mass an object has the more inertia it has. Mass is proportional to inertia
Gravitational force
Two masses in proximity experience an attractive gravitation force. The magnitude of the force is proportional to the product of the two masses and inversely proportional to the square of the distances.
Sun- Earth system
Gravity holds the system together; the sun and the earth exert equal and opposite forces on each other; the inertia of the sun is huge compared to the earth, so the force applied to the sun by the earth can be neglected; the sun is considered to be at rest while the earth moves around it
Electron
Mass of an electron is 9.1 x 10^-28, the mass of an electron is too small to comprehend; the inertia of the electron is so small compared to those of protons or neutrons.
Protons
The mass of protons and neutrons are equal, they are about 1800 times larger than electrons.
Neutrons
The mass of protons and neutrons are equal and they are 1800 times larger than electron.
Charges
Charges can be either positive or negative; charges are determined by the electrons; charges exert electrostatic or Coulombic charges on each other; opposite charges attract and same charges repel; the electrostatic force is stronger than gravity but a much shorter range; charge is quantized meaning you cannot divide charged up into smaller charges
Grams
unit of mass
Coulomb
unit of charge
The (ordinary) hydrogen atom
The simplest atom; it consists of 1 protons and 1 electron; the chemical symbol for hydrogen is H; most atomic matter in the universe is hydrogen; the average distance between proton and electron is .5 Å; the electron move randomly through the vicinity of the proton nucleus; the hydrogen electron spends half the time within .5 Å and the other half outside of the .5 Å.
Classical mechanics
Physical theory that describe the dynamics of systems that are much larger than atoms; gives equations of motions, e.g., paths that bodies follow with time; fails for electronic and atomic motion; predicts the hydrogen atom will collapse—it is unstable.
Quantum Mechanics
Accurately predicts the behavior and stability of an atomic system; gives probable information only so no electron paths are given, you can simultaneously measure the velocity and position of the elctron
Angstrom (Å)
a convient unit for atomic distance
Hydrogen Isotopes
There are three kinds of hydrogen isotopes
All isotopes of hydrogen have 1 electron and 1 proton and use the symbol H.
The 3 H isotopes differ in the number of neutrons in the nucleus
Ordinary hydrogen: 0 neutrons, denoted by 1^H.
Hydrogen two: 1 neutron, denoted by 2^H or D (deuterium)
Hydrogen three: 2 neutrons, denoted by 3^H or T (tritium)
A sample of hydrogen is almost all ordinary hydrogen, containing very small amount of deuterium and trace amounts of tritium.
Hydrogen two 2^H
The 2 superscript is the total number of neutrons and protons in the nucleus (the mass number)
2^H has 2 nucleons
Nucleons
a proton or a neutron
Hydrogen three 3^H
3^H has 3 nucleons: 2 neutrons+ 1 proton= 3 nucleons, but the mass does not equal 3
The Helium atom
All helium atoms have 2 protons and 2 electrons
The chemical symbol is He
2 types of He isotopes: 3^He (1 neutron and 2 protons) and 4^He (2 neutrons and 2 protons)
Atomic number
refers to the number of protons in the nucleus of the given element
nuclide
an atom with a specific number of neutrons
Isotopes are a set of nuclides with the same atomic number
Stable isotopes and Neutrons
Light isotopes usually have # of neutrons = # of protons
12^C: 6 protons & 6 neutrons (6+6=12)
14^N: 7 protons & 7 neutrons (7+7=14)
16^O: 8 protons & 8 neutrons (8+8=16)
18^F: 9 protons & 9 neutrons (9+9=18)
Light isotopes can sometime have # of neutrons that are around the # of protons,
13^C: 6 protons & 7 neutrons (6+7=13 about 12)
Subscript notation for the atomic number
A subscript is sometimes used for the atomic number
Heavy isotopes usually have # of neutrons> # of protons
The generic formula for Andy nuclide is given by A/Z (X)
X- the chemical symbol A- mass number Z- the atomic number
The number of neutrons is A-Z
Half lives of unstable nuclides
Some nucleotides, especially the large ones, are unstable
Overtimes the nucleus fly apart into smaller pieces
Half-life: the amount of time that one- half of a sample will remain and one half is gone (decomposed)
Ions
If an atom gains one or more electron or loses one or more electron it becomes an ion.
An appended negative charge means more electrons than protons (gain electron)
An appended positive charge means less electrons than protons (loses electron)
Solids
Have high densities, the atoms or ions (or molecules) are locked in place but they vibrate
Ionic crystals
Ionic crystals are solids, they contain ions in a regular pattern called a crystal lattice
Glasses
Glasses are solids with no crystal lattice, they have a random arrangement
