Matter

• Chemistry is the study of matter, which is anything that has mass and takes up space
• Matter can change from one form to another
• In a chemical change (chemical reaction), substances are used up and others are formed in their place
• In a physical change, matter does not lose its identity
• A common physical change is a change of state, for example, ice melting to become liquid water
• The scientific method involves testing theories to acquire knowledge
• A fact is a statement based on direct experience
• A hypothesis is a proposed statement to explain a set of facts or their relationship
• A theory is the formulation of an apparent relationship among observed phenomena, verified to some extent
• Exponential notation is used to represent very large or very small numbers as powers of 10
• Significant figures are digits in a number that are meaningful in terms of accuracy or precision
• In multiplication and division, the final answer should have the same number of significant figures as the number with the fewest significant figures
• In addition and subtraction, the answer is given to the same number of decimal places as the term with the fewest decimal places
• When rounding off, if the first digit dropped is 5, 6, 7, 8, or 9, the last digit kept is raised to the next number
• All the rules for significant figures apply to measured numbers and not to counted or defined numbers
• The metric system is used for conversions between units of measurement
• Mass is the quantity of matter in an object, while weight is the result of mass acted upon by gravity
• Temperature can be measured in Fahrenheit, Celsius, and Kelvin scales
• The factor-label method uses conversion factors to change from one system or unit to another
• The three states of matter are gas, liquid, and solid, each with distinct properties
• Density is the ratio of mass to volume, commonly expressed in g/mL for liquids and solids, and g/L for gases
• Specific gravity compares the density of a substance to water as a standard
• Energy is the capacity to do work, and can be kinetic or potential
• Specific heat is the amount of heat necessary to raise the temperature of 1.00 g of a substance by 1.00 °C
• Liquids have loosely packed particles that can move past each other freely. They take the shape of their container.
• Volume is the space occupied by an object, while density is how closely packed particles are together within that volume.
• Solids have tightly packed particles that vibrate in a fixed position. They have a definite shape and volume.
• Matter can be classified into solid, liquid, gas, or plasma based on how closely the particles are packed together and how freely the particles can move.
• Mass is measured in kilograms (kg).
• The mass of an object is the amount of matter it contains.
• Gases have very loose particle packing with lots of empty spaces between them. Gases do not have a definite shape but fill any available space.
• Gas molecules have high energy levels due to collisions with one another and the walls of their container.
• Solids have tightly packed particles arranged in a regular pattern, giving them definite shapes and volumes.
• The three states of matter are solid, liquid, and gas.
• Gases have widely spaced particles that move rapidly in random directions. They fill any container they're placed into.
• Gases have widely spaced particles that move rapidly and randomly in all directions. They fill any container they're placed in and have no definite shape or volume.
• The three states of matter (solid, liquid, gas) differ in terms of particle arrangement and motion.
• Density is calculated as mass divided by volume.
• Gases have widely spaced particles with lots of empty spaces between them. They do not have a definite shape but fill the entire container they occupy.
• Liquid particles are close enough to touch one another but still able to flow around each other.