Introduction to Chemistry and Matter

Chemistry definition and branches

• Chemistry studies matter and its changes and addresses why and how substances merge or separate, forming new substances.
• Chemistry explains the world and how substances interact with energy.
• Organic, Inorganic, Analytical, Physical chemistry, and Biochemistry are branches of chemistry.

Matter

• Matter is anything with mass that occupies space
• Atoms are the components of matter.
• Each element consists of the same type of atoms.
• Matter is everything you can see and touch around us
• Energy, light, sound, time, rainbows, gravity, emotions, memories, dreams, magnetism, information and vacuums are not considered matter (non-matter).
• Matter has physical and chemical properties.
• Physical properties can be observed without changing a substance - include boiling point, density, mass and volume.
• Chemical properties include flammability, corrosiveness, and reactivity with acid; these can only be observed when a substance is changed into another substance.

Weight

• Weight is a type of force acting on all objects near Earth due to gravity.
• Fg = mg = W (Fg = is force of gravity, m = mass, g = acceleration due to gravity = 9.8m/s2, and W = weight).
• Weight is the force of gravity attracting matter to Earth while mass is simply the amount of matter in an object.
• An object with a mass of 50kg has a weight of 110 lbs on Earth, but on Mars that same object with have a weight of 42 lbs.
• Mass of planets from least to most massive: Mercury (3.30 x 10^23 kg), Mars (6.42 x 10^23 kg), Venus (4.87 x 10^24 kg), Earth (5.97 x 10^24 kg), Uranus (8.68 x 10^25 kg), Neptune (1.02 x 10^26 kg), Saturn (5.68 x 10^26 kg), Jupiter (1.90 x 10^27 kg).
• Earth has an acceleration due to gravity of 9.8 m/s^2.

Atoms and elements

• An atom is the smallest amount of an element and atoms are building block of elements.
• All the elements in the periodic table are examples of atoms.
• Examples of atoms include Hydrogen (H), Iron (Fe), Carbon (C), Argon (Ar), and Calcium (Ca).
• An element has only one type of atom and cannot be broken down into simpler substances by chemical or physical means.
• There are 118 elements on the periodic table.

Molecules and compounds

• A molecule has 2+ atoms combined chemically, and those can be the same or different.
• All compounds are molecules but molecules are not always compounds.
• Examples of Molecules: H2, N2, O2, Cl2, CO2, CO, CH4, NO2, NH3, CaCl2, C6H12O6, C12H22O11, H2O (water), N2 (nitrogen), O3 (ozone), CaO (calcium oxide), C6H12O6 (glucose, a type of sugar) and NaCl (table salt).
• A compound has more than one kind of atom and can be broken down chemically into elements.
• Examples of Compounds: H2O (water), C6H12O6 (glucose), C2H6O (alcohol), NaCl (salt), C2H6O (ethanol), C2H4O2 (vinegar), NH3 (ammonia), C2H4O2 (acetic acid), C4H10 (butane), H2SO4 (sulfuric acid), CH4 (methane), C12H22O11 (sucrose), C3H8 (propane), NaHCO3 (baking soda), N2O (nitrogen).

Atoms and Ions

• An atom contain a nucleus and electrons.
• The Nucleus also contains protons and neutrons.
• Ions are charged chemical species, that are either cations (+) or anions (-).
• Cations possess a positive charge as a result of oxidation, which denotes the loss of electrons: examples inclide Na+ which has loss of one electron, Ca2+ which as lost two electrons, or Mn7+ that has lost 7 electrons.
• Anions possess a negative charge through reduction from the gain/addition of electrons: examples include Cl- has gained 1 electron, O2- has gained 2 electrons, and N3- has gained 3 electrons.
• Atoms contain a nucleus and electrons and the nucleus is the central mass of the atom.
• The nucleus contains of protons and neutrons.
• Electrons are moving (revolving) around the nucleus in orbits (called shells, which represents energy levels).
• J.J. Thomson discovered the electron (e−) in 1896, it has a negative charge, and a mass of 9.1x10^-31 kg.
• Ernest Rutherford discovered the proton (H+) in 1911, it has a positive charge, and a mass of 1.673x10^-27 kg.
• James Chadwick discovered the neutron (n0) in 1932 and it has a neutral (0) charge and has a mass of 1.675x10^-27 kg.
• James Chadwick was a student of Ernest Rutherford, and Ernest Rutherford was a student of J.J. Thomson

Atomic and Mass Numbers

• Atomic number (Z) is the number of electrons and protons in an atom.
• Mass number/Atomic mass (A) sums total of protons and neutrons (P + N = mass number = A)
• To calculate the number of neutrons = A -Z

Isotopes, Isobars, and Isotones

• Isotopes are atoms having the same atomic numbers.
• Hydrogen has 3 isotopes: Protium, Deuterium and Tritium.
• Atomic number is the same in all isotopes of carbon, which is 6.
• Isobars are atoms having the same mass number.
• Isotones are atoms having the same number of neutrons.

Difference between element and compounds

• Elements possess only one type of atom, while compounds contain more than one type of atom.
• Elements cannot be divided by chemical means whereas compounds can be divided.