Chemistry+Vocabulary

__Unit 1, Lesson 2 Vocabulary__

- **hypothesis**: possible explanation for an observation

- **chemistry**: the study of matter and how matter changes

- **properties**: characteristics

//2 Types of "Properties" in Chemistry...//


 * - Physical properties**: all characteristics of a substance except for how they chemically react with other substances. Examples include color, odor, hardness, melting point.

- **Chemical properties**: the characteristics of a substance pertaining to how it reacts with other substances.

__Unit 1, Lesson 3 Vocabulary__

- **matter**: anything that has mass and volume

- **mass**: the amount of substance (or matter) in an object

- **volume**: the amount of space an object takes up

- **balance**: used to measure mass

- **graduated** **cylinder**: used to measure volume

- **meniscus**: the curve at the top of a liquid in a graduated cylinder. Volume should be measured from the bottom of the meniscus.

__Unit 1, Lesson 4 Vocabulary__

- **water displacement**: a method for finding the volume of a solid object where an initial volume of water is subtracted from the volume of the water with the solid object in it. A graduated cylinder is used for this method.

- **dimensional calculation**: a method for finding the volume of a solid object where the length, width, and height are multiplied together. One typically needs a ruler to do this, and the solid object must have a cubic shape.

__Unit 1, Lesson 5 Vocabulary__

- **density**: the mass per unit volume of a substance. (How "compact" the matter in a substance is.)

- **intensive property**: characteristics of substances that do not depend on how much of the substance there is. These characteristics can be used to help identify a substance. (color, hardness, density, melting and boiling point temperatures)

- **extensive property**: characteristics of substances that DO depend on how much of the substance there is. (mass, volume)

__Unit 1, Lesson 6 Vocabulary__

- **chemical symbols**: it's the one or two letter abbreviations that appear on the periodic table for each element.

- **chemical formula**: how a compound is represented symbolically.

- **elements**: considered the building materials of all matter.

- **compounds**: substances that form when elements combine in specific ratios.

- **phases of matter**: solid, liquid, gas, or aqueous.

- **aqueous**: a phase of matter where the substance is dissolved in water.

__Unit 1, Lesson 7 Vocabulary__

- **chemical change** or **chemical reaction**: one substance is transformed into another substance. Elements are not created or destroyed in chemical reactions, they are //rearranged//.

__Unit 1, Lesson 8 Vocabulary__

- **Law of Conservation of Mass**: mass cannot be gained or lost in a chemical reaction.

__Unit 1, Lesson 9 Vocabulary__

- **reactivity:** a property which describes how easily an element will combine with other substances to form new compounds.

- **atomic mass**: the mass of one atom. Alternatively, the amount of matter in one atom of a substance.

- **(atomic mass units)**: the unit used when describing the mass of an atom. It's similar to a //gram// or a //pound// but much, much smaller.

__Unit 1, Lesson 10 Vocabulary__

- **atomic number**: the main whole number within an element's cell on the periodic table. It tells you the number of protons.

- **group**: refers to a vertical column on the periodic table. They could also be referred to as families.

- **period**: refers to a horizontal row on the periodic table.

- **metal**: elements that exist to the left of the stair-step line on the periodic table. They are typically lustrous, malleable, and conductive.

- **nonmetals**: elements that exist to the right of the stair-step line on the periodic table. They are typically **not** lustrous, malleable or conductive.

- **metalloids**: elements that exist on the stair-step line. They tend to have properties of both metals and nonmetals.

__Unit 1, Lesson 11 Vocabulary__

- **atom**: fundamental building block of matter composed of protons and neutrons in a nucleus and electrons outside the nucleus.

- **atomic theory**: states that all matter is made up of atoms.

- **model**: simplified model of something you want to explain. In science, models explain observed behavior and make predictions about what //would// be observed in different circumstances.

- **nucleus**: area in the center of the atom where protons and neutrons are.

- **proton**: positively charged subatomic particle with a mass of 1 amu.

- **neutron:** a subatomic particle with no charge and a mass of 1 amu.


 * -** **electron**: negatively charged subatomic particle with a mass 1/2000 that of a proton or neutron. They are therefore considered mass negligible.

__Unit 1, Lesson 12 Vocabulary__

- **atomic number**: the number of protons in an atom of an element.

__Unit 1, Lesson 13 Vocabulary__

- **mass number**: the number of protons and neutrons added together.

- **average atomic mass**: an average of a large sample of atoms of a particular element that takes into account all the different isotopes of that element. By rounding average atomic mass, you can determine the most common isotope of that element.

__Unit 1, Lesson 14 Vocabulary__

- **radioactive isotopes**: less stable isotopes that eject small pieces of the nucleus from the atom, thereby becoming more stable.

__Unit 1, Lesson 17 Vocabulary__

- **flame test:** by burning chemicals in a flame, their colors can be observed and the identity of metallic elements present determined.

__Unit 1, Lesson 18 Vocabulary__

- **valence shell:** the outermost shell occupied by electrons in an atom

- **valence electrons**: the electrons that occupy the outermost shell in an atom

- **core electrons**: the electrons that are NOT in the outermost shell of an atom

- **electronegativity**: the ability of an atom to hold onto or pull in valence electrons (specifically in bonding situations)

__Unit 1, Lesson 19 Vocabulary__

- **ion**: charged atom, due to an imbalance of protons and electrons

- **cation**: a positively charged atom due to the loss of electrons

- **anion**: a negatively charged atom due to the gaining of electrons

__Unit 1, Lesson 20 Vocabulary__

- **ionic compound**: when oppositely charged ions stick together by electromagnetism. Since metals form cations (positive) and nonmetals form anions (negative), ionic compounds are between metals and nonmetals.

__Unit 1, Lesson 22 Vocabulary__

- **polyatomic ions**: ions that consist of two or more elements.

- **monatomic ions**: ions that consist of one element.

__Unit 2, Lesson 1 Vocabulary__


 * - molecular formula:** a chemical formula for a molecular covalent compound

__Unit 2, Lesson 2 Vocabulary__


 * - structural formula**: diagram that shows how atoms are arranged and how they are bonded in a molecule.


 * - isomer**: two different structural formulas with the same molecular formula (same formula, different structure)

__Unit 2, Lesson 4 Vocabulary__


 * - Lewis Dot structure:** a diagram of a molecule that uses dots to represent valence electrons.


 * - Lewis Dot symbol:** the symbol (abbreviation) for an element with dots around it that show the number of valence electrons.


 * - bonded pairs:** pairs of electrons that are shared between two atoms. They are between atoms in Lewis Dot structures.


 * - lone pair:** pair of electrons that are NOT shared between two atoms.

__Unit 2, Lesson 5 Vocabulary__


 * - octet rule:** atoms will bond until they get 8 valence electrons.


 * - double bond:** this is when four electrons are shared between two atoms. It is represented as a double line.


 * - triple bond:** this is when six electrons are shared between two atoms. It is represented as three lines.