a tested possible explanation of what is observed
applying logic and reason to observation
closeness of a measurement to accepted value
degree of exactness of a measurement
a possible answer to a question
variable which is measured in an experiment
variable which is manipulated in an experiment
summary of observation
causes the formation of a different substance
substance with only one type of molecule
matter with only one type of particle
mass divided by volume
two or more substances, not chemically combined
substance with only one type of atom
how a substance reacts with other substances
does not change the identity of a substance
property of matter that is easily observed or measured
anything that occupies space or has weight
a trait that helps identify matter
the study of the changes & properties of matter
a phase change from solid to gas
force per unit area
state of matter made of ions
law of conservation of mass
mass is neither created nor destroyed
the ability to move or change matter
the total energy of a substance's molecules
resistance to flow in a fluid
law of conservation of matter
matter is neither created nor destroyed
the average kinetic energy of a substance's molecules
kinetic molecular theory
explains the state of matter
electrons found in the outermost energy level
developed modern atomic theory
positively charged atomic particles
neutral atomic particles
compared the atom to the solar system
part of the atom which contains protons and neutrons
performed the cathode ray tube experiment
performed the gold foil experiment
first used the word "atom"
negatively charged atomic particles
part of the atom which contains energy levels
consists of one proton and one electron
consists of one proton, two neutrons, and one electron
number of protons + number of neutrons
tells number of protons in a nucleus
greek word for indivisible
consists of one proton, one neutron, and one electron
same element with different mass
the chemical and physical properties of elements are periodic functions of their atomic number
most useful metalloid
arranged elements by atomic mass
gaining or losing electrons
vertical columns on the periodic table
most useful alkaline earth metal
horizontal rows on the periodic table
arranged elements by atomic number
elements that are brittle but conduct electricity
alkaline earth metals
organic compound that contains H, C, and O
simplest series of hydrocarbons; does not have double bonds
series of hydrocarbons that has an OH group
organic compound that contains H and C
biological polymer made of amino acids
series of hydrocarbons that has double bonds
compounds that contain C, H, O, and N
attractive force that holds atoms of a compound together
shows how atoms are arranged in a compound
attraction between a positive metal ion and electrons
attractive force of sharing electrons
attractive force of transferring electrons
a group of nonmetals that act like an ion
catalyst for living things
reaction that releases energy
substances formed by chemical change
specific substance affected by enzymes
how quickly a chemical reaction occurs
formation of a solid in a chemical reaction
Le Chatilier's Principle
an equilibrium subjected to stress will shift to relieve stress
reaction which absorbs energy
original substances before a chemical change occurs
using an electric current to decompose a compound
fragment of a molecule with an available electron
forward reaction rate is equal to the reverse rate
an element transforms into a different element
proceeds because of a single action
consists of 2 protons and 2 neutrons
an unstable nucleus emits particles of energy
first experienced gamma rays
discovered alpha particles
the process of splitting a large nucleus into fragments
process where light nuclei combine into a larger nucleus
consist of electrons emitted by a nucleus
smallest amount of fuel needed for a chain reaction
time needed for one-half of a radioactive sample to decay
release of high-energy neutrons by a neutron-rich nucleus
strong nuclear force
holds protons and neutrons together in a nucleus
consists of massless, pure energy
radiation that occurs naturally
What are the smallest particles of compounds?
What classes of matter are considered to be substances?
elements and compounds
What are the signs of a chemical change?
1. gas production
3. energy change
4. color change
What are the four basic classifications of matter?
4. heterogeneous mixture
List several examples of chemical properties.
List several examples of physical properties.
color, density, freezing point, melting point
What happens to temperature during a phase change?
What phases of matter have a definite shape?
What phases of matter have definite volume?
liquids and solids
How do the particles of solids behave?
adjacent, locked in place; vibrate; definite volume and shape
How do the particles of liquids behave?
adjacent, free to move; indefinite shape - definite volume
How do the particles of gases behave?
very spread out, free to move; indefinite volume and shape
How does molecular motion relate to temperature?
higher temp = faster motion
What causes pressure in fluids?
collisions with the container walls
What principle is applied when squeezing out toothpaste?
What states of matter are considered to be fluids?
gases and liquids
How is pressure calculated?
force divided by area
How do the number of protons and electrons compare in a neutral atom?
they are equal
What is the relationship between protons, neutrons, electrons, and mass number?
protons + neutrons = mass number
How do protons and neutrons compare to each other?
about the same size
What causes the mass difference between isotopes of the same element?
different number of neutrons
Where are electrons found in the atom?
orbitals and energy levels
What element was used as the standard for atomic mass?
How did Bohr describe the atom?
What determines an element's identity?
number of protons
What particles are found in the nucleus of an atom?
protons and neutrons
How did JJ Thompson describe the atom?
What was proven by the gold foil experiment?
positive nucleus; most of mass in nucleus; atom is mostly empty space
Where are nonmetals found on the periodic table?
right of the zig-zag line
What is the meaning of the word halogen?
How do transition metals compare to metals further left of the periodic table?
harder, less reactive, less shiny, more practical
In what order did Mendeleev arrange his periodic table?
increasing atomic mass
What type of ion do nonmetals form?
negative - anion
What elements on the periodic table are synthetic?
above atomic number 92
What elements on the periodic table are radioactive?
above atomic number 92
What type of ions do metals form?
positive - cation
Where are metals found on the periodic table?
left of the zig-zag line
In what order is today's periodic table arranged?
by atomic number
What is the name of the simplest alkane?
What type of organic compound is vital to living things?
What is the structure of DNA?
What types of organic compounds exist as polymers?
plastics, rubber, DNA, proteins
What is a polyatomic ion?
group of covalently bonded atoms that bond ionically
List the properties of network structure compounds.
hard, brittle, high melting and boiling points
List some properties of molecular structure compounds.
low melting and boiling points
How are chemical equations balanced?
add numbers in front of symbols / formulas
Where are reactants found in a chemical equation?
on the left
Le Chatlier's principle applies to what type of chemical reaction?
How does temperature affect reaction rate?
higher temperature = faster reaction
What is the relationship between surface area and reaction rate?
greater surface area = faster reaction
When is pressure a factor on reaction rate?
when reactants are a gas
What type of reaction is electrolysis?
How do catalysts affect reaction rate?
speeds it up
What happens to bonds during chemical reactions?
reactant bonds are broken; product bonds are formed
Identify the five common types of chemical reactions.
1. synthesis: element + element ---> compound
2. decomposition: compound ---> element + element
3. single displacement: E + C ---> E + C
4. double displacement: C + C ---> C + C
5. combustion: hydrocarbon + oxygen ---> water + CO2
What are the products of a fission reaction?
energy + neutrons
What nuclear reaction is on the Sun?
What type of nuclear reaction was used in the World War II bombs?
How does the nucleus change during alpha decay?
atomic number decreases by 2
What type of radioactive particle has no mass?
What are the fuels for fission reactions?
plutonium and uranium
Compare the types of radioactive particles in terms of penetrating ability.
alpha - least penetrating, then beta, then neutron then gamma is most
How is carbon dating used?
to find the age of once-living things
How does the nucleus decay during gamma decay?
Who produced the first man-made fission reaction?
What happens to the nucleus during beta decay?
the atomic number increases by 1