Chapter One: Matter, Energy, and Measurement Flashcards
What is Matter?
Anything that occupies space and has mass. It is the physical material of the universe and is comprised of elements.
What is a Property?
The only characteristic that allows us to recognize a particular type of matter and to distinguish it from other types.
What is an Element? How many are there?
There are 118 elements. An element is a substance that cannot be broken down into simpler substances. Each element is composed of a unique one of atom.
What is an Atom?
The smallest representative particle of an element. The almost infinitely small building blocks of matter.
What is a Molecule?
A chemical combination of two or more atoms.
Even the smallest difference in composition can cause profound differences in properties.
What does a Chemist do? (3)
- Make new types of matter: materials, substances, or combinations of substances with desired properties
- Measure the properties of matter
- Develop models that explain and/or predict the properties of matter
Gas
No fixed shape or volume
Uniformally fills container
Can be compressed to occupy a smaller volume or expand to occupy a larger one
Liquid
Distinct volume
Takes shape of its container
Not compressible
Solid
Definite shape and volume
Not compressible
What is a Pure Substance?
Matter that has a fixed composition and distinct properties that do not vary from sample to sample Either an element or a compound
What is a Compound?
Substances composed of two or more elements (two or more kinds of atoms)
What elements account for over 90% of the human body?
Oxygen
Carbon
Hydrogen
Law of Constant Composition (Law of Definite Proportions)
a law that states that the elemental composition of a compound is always the same
Heterogenous
Vary in texture and appearance
Homogenous
(Solution) Uniform
What is a Physical Property? Examples?
Properties that can be measured without changing the composition of a substance
Color, Freezing Point, Odor, Melting Point, Boiling Point, and Hardness
What is a Chemical Property? Examples?
Properties that describe the way a substance may change, or react, to form other substances Flammability, Reactivity, Oxidation
What is an Intensive Property? Examples?
Does not depend on the amount of sample being examined
Temperature and Melting Point
What is an Extensive Property? Examples?
Dependent on the amount of sample
Mass and Volume
Define a Physical Change:
When a substance changes its physical appearance but not its composition (changes of state)
Define a Chemical Change:
When a substance is transformed into a chemically different substance (chemical rxn)
What is Distillation?
A separation process that depends on the different abilities of substances to form gases