Chemistry

• Dalton's Atomic Theory: Atom is an indivisible particle.
• Dalton's Atomic Theory: Atom can neither be created nor destroyed.
• Dalton's Atomic Theory: Atoms of an element are identical in size, shape, mass and in other properties.
• Dalton's Atomic Theory: Atom of different elements are different in their properties.
• Dalton's Atomic Theory: Atoms combine with each other in small whole numbers.
• Dalton's Atomic Theory: All chemical reactions are due to the combination or separation of atoms.
• John Dalton (1766-1844) - English chemist who proposed that all matter was made up of tiny particles called atoms
• Matter: anything that has mass and occupies space.
• Mixtures: combinations of two or more substances in which each substance retains its own chemical identity and hence its own properties.
• Physical Change: change of state or phase.
• Chemical Change: transformation in which substances are converted in other substances.
• Compound: pure substance formed by combining two or more elements in definite proportions.
• Element: pure substance composed of only one kind of atom.
• Isotopes: different forms of the same element with the same number of protons but differing numbers of neutrons.
• Heterogeneous Matter (variable composition) can be converted by physical means into Homogeneous Matter.
• Homogeneous Matter can be converted by physical means into Pure Substances (fixed composition).
• Compounds can be converted by chemical means into Elements
• Law of Conservation of Mass: Mass cannot be created or destroyed in a chemical reaction.
• Law of Definite Composition/Proportions: The elements in a compound are always in a definite proportion
• Law of Multiple Proportions: When two elements form more than one compound, the masses of one element that combine with a fixed mass of another element bear simple whole-number ratios to each other.
• Atomic Number: The number of protons in an atom.
• Mass Number: The sum of the numbers of neutrons and protons in an atom.
• Isotopes: atoms of the same element with different numbers of neutrons.
• Atomic Mass (weight): average mass of the atoms of an element in amu: mass in g of one mole of the element.
• Mole (mol): quantity of a given substance that contains as many molecule or formula units as the number of atoms in exactly 12 g of carbon-12; consists of 6.02 x ^23 particles.
• Molar Mass: mass of one mole of a substance in grams.
• Percentage Composition: The percentage of each element in a compound.
• Percentage Composition = Mass of each element / Total mass of sample x 100
• % Composition =[ [n x MM (Element)]/MM (Compound)] x 100
• Molecule: definite group of atoms that are chemically bonded together.
• Ion: electrically charged particle obtained from an atom or chemically bondede group of atoms by adding or removing electrons
• Chemical Formula: A chemical formula is a symbolic representation of the elements in a compound.
• Empirical Formula (Simplest Formula): formula with the smallest integer subscripts.
• Molecular Formula: chemical formula that gives the exact number of different atoms of an element in a molecule.
• WATER

  Molecular Formula: H2O

  Empirical Formula: H2O
• Hydrogen Peroxide

  Molecular Formula: H2O2

  Empirical Formula: HO
• ETHANE

  Molecular Formula: C2H6

  Empirical Formula: CH3
• Molecular Mass/Weight (MW): the sum of the atomic masses/weights of all the atoms in a molecule.
• Formula Mass/Weight (FW): the sum of the atomic masses/weights of all atoms in a formula unit of the compound, whether molecular or not.
• Empirical Formula Weight (EFW): the sum of the atomic massses divided by the weights of all the atoms in an empirical formula.