Chemistry Midterm

Chapter 1 terms

• Solid - matter has definite volume and definite shape

• Atom - is the smallest unit of an element that maintains the chemical identity of that element

• Compound - a substance that can be broken down into simple stable substances. Each compound is made from the atoms of two or more elements that are chemically bonded.

• Metalloid - an element that has some characteristics of metals and some characteristics of nonmetals

Chapter 2 terms

• Hypothesis - a possible explanation for a problem using what you know and what you observe

• Conversion factor - a ratio derived from the equality between two different units that can be used to convert from one unit to another.

• Dependent variable - changes according to the changes of the independent variable

• Independent variable - the variable that is changed to test the effect on the dependent variable

• Scientific law - a statement about what happens in nature and that seems to be true all the time

Chapter 3 terms

• JJ Thomson - Cathode-ray tube experiments measured the charge-to-mass ratio of an electron. Thomson proposed a model for the atom that is called the plum pudding model.

• Ernst Rutherford - The results of their gold foil experiment led to the discovery of a very densely packed bundle of matter with a positive electric charge.

  Isotopes - Atoms of the same element that have different masses

• Mole - The amount of a substance that contains a number of particles equal to the number of atoms exactly 12 or carbon -12

Chapter 4 terms

• Quantum numbers - specify the properties of atomic orbitals and the properties of electrons in orbitals

• Aufbau’s principle - Shows the order in which electrons occupy orbitals. According to the Aufbau’s principle, an electron occupies the lowest energy orbital that can receive it.

• Hund’s rule - Requires placing as many unpaired electrons as possible in separate orbitals in the same sub level. According to the Hund’s rule, orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin state.

• Octet - the eight-electron arrangement in the outer electron shell of the noble-gas atoms

• Highest Occupied energy level - a electron-containing main energy level with the highest principal quantum number

Chapter 5 terms

• Ionization energy - energy required to remove one electron from a nuetral atom of an element

• Electron affinity - the energy change that occurs when an electron is acquired by a neutral atom

• Electronegativity - a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound

• Cation - positively charge ion

• Anion - negatively charge ion