Chapter 1: Atoms Flashcards
How are the properties of matter determined?
By the structure of the atoms and molecules that compose it. A small change in structure, such as a different shape, results in a significant change in properties.
Define matter.
Anything that occupies space and has mass.
Define atoms.
A submicroscopic particle that constitutes the fundamental building block of ordinary matter; the smallest identifiable unit of an element.
Define molecules.
Two or more atoms joined chemically in a specific geometrical arrangement.
Define chemistry.
The science that seeks to understand the properties of matter by studying the structure of the particles that compose matter.
Define substance.
A specific instance of matter, such as air, water, or sand.
Define state.
A classification of a form of matter as a solid, liquid, or gas.
How is the state of matter classified?
It depends on the relative positions of the particles and how strongly they interact with one another (relative to temperature).
How is matter classified?
By its state or by its composition.
Define composition.
Refers to the type of particles that compose matter; by composition is one way to classify matter.
Define solid.
Particles that compose solid matter attract one another strongly and therefore pack closely to each other in fixed locations. Although the particles vibrate, they do not move around or past each other. Fixed volume and rigid shape.
Define liquid.
The particles that compose liquid matter pack about as closely as particles do in solid matter, but slightly weaker attractions between the particles allow them to move relative to each other, giving liquids a fixed volume but not a fixed shape. Liquids assume the shape of their container.
Define gas.
The particles that compose gaseous matter attract each other only very weakly - so weakly that they do not clump together as particles do in a liquid or solid. Instead, the particles are free to move large distances before colliding with one another. Gases always assume the shape and volume of their container.
What state of matter can be compressed?
Gases, because there is so much empty space between atoms or molecules in the gaseous state.
Define pure substance.
A substance made up of only one type of atom or molecule, and its composition is invariant.
Define mixture.
A substance composed of two or more different types of atoms or molecules that can be combined in variable proportions.
Define element.
A substance that cannot be chemically broken down into simpler substances.
Define compound.
A substance composed of two or more elements in fixed, definite proportions.
Define heterogenous mixture.
A mixture in which the composition varies from one region to another.
Define homogeneous mixture.
A mixture with the same composition throughout.
Define hypothesis.
A tentative interpretation or explanation of an observation. A good hypothesis is falsifiable.
Define experiment.
A highly controlled procedure designed to generate observations that may support a hypothesis or prove it wrong.
Define scientific law.
A brief statement or equation that summarizes past observations and predicts future ones.
Define law of conservation of mass.
The law stating that matter is neither created nor destroyed in a chemical reaction.
Define theory.
A proposed explanation for observations and laws, based on well-established and tested hypotheses; a theory presents a model of the way nature works and predicts behavior beyond the observations and laws on which it was based.
Who proposed the atomic theory?
John Dalton
What laws led to the development of the atomic theory?
- law of conservation of mass
- law of definite proportions
- law of multiple proportions
