Chapter 1 - Matter & Change Flashcards
Define chemistry:
the study of matter: its composition, structures, properties, changes it undergoes, and energy accompanying these changes.
Define matter:
anything that has mass and volume.
Define element:
pure substance that cannot be physically or chemically broken down.
- made up of atoms with the same atomic number and same number of protons
What is an example of an element?
carbon
What are the three main types of elements?
metals, nonmetals, and metalloids
List some of the characteristics of metals:
- ductile (able to be drawn out into a thin wire)
- malleable (hammer into thin sheets)
- tensile strength (resist breaking under pressure)
- good conductors of heat & electricity
- luster (shiny)
List some of the characteristics of nonmetals:
- poor conductors of heat & electricity
- brittle (shatter easily)
- Group 18 (Noble Gases; nonreactive)
List some of the characteristics of metalloids:
- possess some characteristics of metals and nonmetals
- utilized as semiconductors to carry electric current
Define molecule:
consists of two or more elements that are bonded together.
Give an example of a molecule:
O2
What are the seven diatomic molecules?
Br, I, N, Cl, H, O, F
Define compound:
a pure substance that consists of two or more different atoms bonded together in fixed proportions.
- can be chemically separated/decomposed into a simpler substance; always homogeneous
What is an example of a compound?
H2O
Define homogeneous mixture:
even distribution of two or more different substances mixed together.
List a few examples of a homogeneous mixture:
salt water, water, air, stainless steel, sugar in water, Kool-Aid, et cetera.
Define heterogeneous mixture:
uneven distribution of two or more different substances mixed.
List a few examples of a heterogeneous mixture:
oil and water, granite, wood, chicken noodle soup.
What methods can be used to separate a homogeneous mixture?
distillation, evaporation, crystallization, chromatography.
What methods can be used to separate a heterogeneous mixture?
filtration, decantation.
Define physical property:
characteristics that can be observed or measured without changing the identity of the substance.
What is an example of a physical property?
melting or boiling property
Define physical change:
a change in a substance that does not involve a change in the identity of the substance.
What are some examples of physical changes?
grinding, cutting, melting and boiling a material.
Define chemical property:
a substance’s ability to undergo changes that transform it into different substances.
What is an example of a chemical property?
the ability of charcoal to burn in air.
Define chemical change:
a substance is converted into different substances.
What is an example of a chemical change?
carbon and oxygen react to produce carbon dioxide, water vapor, and ash that did not react remains.
Define the Kinetic Molecular Theory:
particles of matter are always in motion.
What crucial components make up the Kinetic Molecular Theory?
- the higher the temperature of the substance is, the faster the particles move
- at the same temperature, more massive particles move slower than less massive ones
What does a solid have?
definite shape and volume
What does a liquid have?
definite volume, but indefinite shape
What does a gas have?
no definite shape or volume
Define the heating curve:
shows a change of a substance starting with the substance as a solid. Changes represented on a heating curve are endothermic because heat is being absorbed by the substance.
What does it mean if an endothermic reaction is happening?
heat is being absorbed
Define the cooling curve:
shows a change of a substance starting with the substance as a gas. Changes represented on a cooling curve are exothermic because heat is being released by the substance.
What does it mean if an exothermic reaction is happening?
heat is being released
