The Study of Matter

What is chemistry? Chemistry: the study of matter and the transformation it undergoes Matter: anything that has mass and takes up space Mass: a measure of the amount of matter Mass vs. weight: Weight is the force with which the earth pulls down an object

The Beginning of Chemistry Democritus ( BC) Greek philosopher First to propose the idea that matter was indivisible Coined the term “atom” Believed that atoms could not be created, destroyed, or further divided

Aristotle ( BC) Greek philosopher Believed that all matter was consisted of four elements: earth, water, air, and fire Rejected Democritus’s atomic theory Believed that matter can always be divided

Alchemists (~300 BC – 165 AD) Believed Aristotle’s theory of matter Believed that objects could transform into other objects (transmutation) Aimed to change common metals into gold

Antoine Lavoisier (1777) French chemist Considered the “Father of Modern Chemistry” Developed the concept that a simple element cannot be broken down by any known method of chemical analysis Developed theory that chemical compounds form from elements

Matter and Its Properties Objectives: -Distinguish between the physical and chemical properties of matter -Classify changes of matter as physical or chemical -Explain the gas, liquid, and solid states of matter in terms of particles -Distinguish between a mixture and a pure substance

Basic Building Blocks of Matter What is matter made of? Atom: the smallest unit of an element that maintains the properties of that element Atoms make up elements and compounds Element: a pure substance made of only one kind of atom Ex: carbon, hydrogen, oxygen Compound: a substance that is made from the atoms of two or more elements that are chemically bonded Ex: water (H 2 O), salt (NaCl)

States of Matter 3 common states of matter: Solid: a form of matter that has a definite shape and definite volume The particles of matter are tightly packed Liquid: a form of matter that flows, has definite volume, but no definite shape The particles in a liquid are less closely packed Gas: a form of matter that doesn’t have definite volume nor definite shape, but fills and takes the shape of its container The particles in gases are very far apart

Properties & Changes in Matter Every substance, whether it is an element or compound has characteristic properties Properties are either intensive or extensive Extensive property: a property that depends on the amount of matter that is present Intensive property: a property that does not depend on the amount of matter present

Intensive vs. Extensive Examples: Boiling pointIntensive VolumeExtensive Mass_________ Color_________ Smell_________ Extensive Intensive

Properties can be grouped into 2 general types: physical or chemical Physical Property: property that can be observed without changing the identity of the substance Observed with senses Determined without destroying matter Physical change: a change in a substance that does not involve a change in the identity of the substance A change in size, shape, or state of matter No new substance is formed The change can be undone

Chemical Property: property that describes the ability of a substance to undergo changes in identity Indicates how a substance reacts with something else Matter will be changed into a new substance after the reaction Chemical change: a change in which one or more substances are converted into different substances The change cannot be undone! Signs of a chemical change: Change in color or odor Formation of a gas Formation of a solid Change in light or heat

Physical vs. Chemical Examples: Rusting ironChemical Dissolving in waterPhysical Burning a log___________ Melting ice___________ Grinding spices ___________ Chemical Physical

Classification of Matter Matter can be classified into one of two groups: pure substances and mixtures Pure substance: a sample that has a specific and constant chemical composition Cannot be separated Either compounds or elements

Mixture: a blend of 2 or more kinds of matter, each of which retains its own identity and properties Can be separated by different methods 2 types of mixtures: Homogeneous: the same in composition Ex: glass of orange juice Heterogeneous: different in composition Ex: chicken noodle soup