# The Vocabulary.....

## Here is the Vocabulary for chapter 2...

section 2.1-

Base Unit- is a defined unit in a system of measurement that is based on an object or event in the physical world and is independent of other units.

Second- is the SI base unit for time.

meter- is the SI base unit for length.

kilogram- is the SI base unit for mass; about 2.2 pounds.

derived unit- a unit defined by a combination of base units.

liter- is the metric unit for volume equal to one cubic decimeter.

density- a ratio that compares the mass of an object to its volume.

kelvin- is the SI base unit of Temperature.

Section 2.2-

scientific Notation- it expresses numbers as a multiple of two factors- a number between 1 and 10, and 10 raised to a power or exponent; makes it easier to handle extremely large or small measurements.

conversion factor- is a ratio of equivalent values used to express the same quantity in different units; is always equal to 1 and changes the units of a quantity without changing its value.

dimensional analysis- a problem-solving method that focuses on the units that are used to describe mater.

Section 2.3-

accuracy- refers to how close a measured value is to an accepted value.

precision- refers to how close a series of measurements are to one another; precise measurements show little variation over a series of trials but may not be accurate.

percent error- is the ratio of an error to an accepted value.

significant figure- the number of all known digits reported in measurements plus one estimated digit.

Section 2.4-

graph- is a visual representation of information, such as a circle graph.

## Here is the vocabulary for chapter 3

Section 3.1-

substance- a form of matter that has a uniform and unchanging composition; also known as pure substance.

physical property- a characteristic of matter that can be observed or measured without changing the sample's composition.

extensive property- a physical property, such as mass, length, and volume, that is dependent upon the amount of substance present.

intensive property- a physical property that remains the same no matter how much of a substance is present.

chemical property- the ability or inability of a substance to combine with or change into one or more new substances.

states of matter- the physical forms in which all matter naturally exists on Earth- most commonly as a solid.

solid- a form of matter that has its own definite shape and volume, is incompressible, and expands only slightly when heated.

liquid- a form of matter that flows, has constant volume, and takes the shape of its container

gas- a form of matter that flows to conform to the shape of its container, fills the containers entire volume, and is easily compressed.

vapor- gaseous state of a substance that is a liquid or a solid at room temperature

section 3.2

physical change- a type of change that alters the physical properties of a substance but does not change its composition.

chemical change- a process involving one or more substances changing into new substances; also called a chemical reaction

law of conservation of mass- states that mass is neither created nor destroyed during a chemical reaction but is conserved.

section 3.3

mixture- a physical blend of two or more pure substances in any proportion in which each substance retains its individual properties; can be separated by physical means.

heterogeneous mixture- is one that does not have a uniform composition and in which the individual substances remain distinct.

homogeneous mixture- is one that has a uniform composition throughout and always has a single phase; aslo called a solution.

solution- a uniform mixture that may contain solids, liquids, or gases; also called a homogeneous mixture

filtration- a technique that uses a porous barrier to separate a solid from a liquid.

distillation- a technique that can be used to physically separate most homogeneous mixtures based on the differences in the boiling points of the substances involved.

crystallization- a separation technique that produces pure solid particles of a substance from a solution that contains the dissolved substance.

chromatography- a technique that is used to separate the components of a mixture based on the tendency of each component to travel or be drawn across the surface of another material.

section 3.4

element- is a pure substance that cannot be broken down into simpler substances by physical or chemical means.

periodic table- is a chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns arranged by increasing atomic number.

compound- is a chemical combination of two or more different elements; can be broken down into simpler substances by chemical means and has properties different from those of its component elements.

law of definite proportions- states that, regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.

percent by mass- is a percentage determined by the ratio of the mass of each element to the total mass of the compound.

law of multiple proportions- states that when different compounds are formed by the combination of the same elements, different masses of one element combine with the same mass of the other element in a ratio of small whole numbers.