Chapter 1 Flashcards
Define Chemistry
The science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules
Basic steps of scientific method
Observation
Hypothesis
Experiment
Law/Theory
Hypothesis
A tentative interpretation or explanation of the observations
Experiment
Highly controlled procedures designed to generate observations that may confirm or refute a hypothesis
Scientific law
WHAT;
A brief statement that summarizes past observations and predicts future ones
Theory
WHY;
A model for the way nature is and tries to explain not merely what nature does but why; often predicting behavior far beyond the observations or laws from which they were developed.
Matter
Anything that occupies space and mass
Pure Substances
Mixtures
Solids
Atoms or molecules pack close to each other in fixed locations. Vibrate, but do not move around or past each other.
Fixed volume and rigid shape
Crystalline or amorphous
Crystalline Solid
A solid where atoms or molecules are in patterns with long-range, repeating order. Geometric shape and arrangement of atoms (most times)
Eg. salt, diamonds
Amorphous solid
A solid where atoms or molecules do not have any long-range order.
E.g glass and plastic. Possible intermediate between solids and liquids. Atoms are fixed in room temperature, but no long range structure and no distinct melting points
Liquid matter
Atoms or molecules are tightly packed, but are free to move relative to each other.
Fixed volume
No fixed shape- Assume shape of container
Gaseous matter
Atoms or molecules have lots of space between them and are free to move relative to one another, making gasses COMPRESSIBLE.
Assume shape AND volume of container
E.g. at room temp, helium, nitrogen, carbon dioxide.
Element
A substance that cannot be chemically broken down into simpler substances
Compound
A substance composed of two or more elements in a fixed definite proportion
Pure substance
Made up of only one component and composition is invariant. Components can be individual atoms or groups of atoms joined together.
Elements and Compounds
Mixture
Variable in composition
Two or more components in proportions that can vary from one sample to another.
Heterogeneous or homogeneous
Homogeneous Mixture
Same composition throughout. Uniform composition because atoms or molecules that compose them mix uniformly.
Heterogeneous Mixture
The composition varies from one region of the mixture to another. Made up of distinct regions because the atoms that compose them are separate.
Physical property
A property that a substance displays without changing its composition
e.g. odor, taste, color, appearance, melting point, boiling point, and density
Chemical Property
A property that a substance displays only by changing its composition via a chemical change.
e.g. flammability, corrosiveness, acidity, toxicity
Physical Change
Changes that alter only state or appearance
Chemical change
Changes that alter the composition of matter. Atoms rearrange, transforming the original substances into different substances.
Energy
Capacity to do work. Work is the action of a force through a distance. Total energy is sum of its kinetic energy, potential energy, and thermal energy.
Kinetic Energy
Energy associated with an objects motion
