atom
The basic particle from which all elements are made.
element
A pure substance that cannot be broken down into any other substances by chemical or physical means.
molecule
A group of two or more atoms held together by chemical bonds.
electron
A tiny, negatively charged particle that moves around the outside of the nucleus of an atom.
nucleus
The central core of an atom which contains protons and neutrons.
proton
Small, positively charged particles that are found in the nucleus of an atom.
neutron
A small particle found in the nucleus of an atom, with no electrical charge.
energy level
The specific amount of energy an electron has.
+1
A proton has a charge of _____ ?
-1
An electron has a charge of _____ ?
zero
A neutron has a charge of _____ ?
atomic number
The number of protons in the nucleus of an atom.
isotope
Atom with the same number of protons and different numbers of neutrons.
mass number
The sum of the protons and neutrons in an atom.
12
Carbon has 6 protons and 6 neutrons in its nucleus. What is its mass number?
atomic mass
The average mass of all the isotopes of that element.
periodic table
An arrangement of elements showing the repeating pattern of their properties.
Dimitri Mendeleev
Who created the first periodic table in 1869?
chemical symbol
An abbreviation of an element's name in English or Latin. Example: Potassium = K
period
Elements in the same row in the periodic table.
group
Elements in the same column in the periodic table. Also known as families.
increasing atomic mass
How did Mendeleev arrange the elements in his periodic table?
increasing atomic number
How are modern periodic tables arranged?
metal
Elements that are good conductors of electric current and heat. They also tend to be shiny and bendable.
luster
Shiny and reflective.
malleable
A material that can be hammered or rolled into flat sheets or other shapes.
ductile
A material that can be pulled out, or drawn, into long wires.
thermal conductivity
The ability of an object to transfer heat.
electrical conductivity
The ability of an object to carry electric current.
reactivity
The ease and speed with which an element combines, or reacts with other substances.
corrosion
The deterioration of a metal due to a chemical reaction in the environment.
alkali metals
The most reactive metals. Found in Group 1 in the periodic table.
alkaline earth metals
These metals are harder and denser, and melt at higher temperatures. Found in Group 2 in the periodic table.
transition metals
Hard and shiny solids. High melting points and high densities. Found in Groups 3-12 in the periodic table.
Lanthanides and Actinides
The two rows placed below the main part of the periodic table.
nonmetal
An element that lacks most of the properties of a metal. Poor conductors of electric current and heat. Dull and brittle.
Copper. The further to the right you move on the periodic table the less reactive is the element.
Period 4 of the periodic table contains the elements potassium, calcium, and copper. Which is the least reactive? Why?
diatomic molecule
A molecule consisting of two atoms.
halogens
salt forming". Found in Group 17.
It separates the metals from the nonmetals
What does the zigzag line separate in the periodic table?
noble gases
The elements in Group 18 in the periodic table.
metalloid
An element that has some characteristics of both metals and nonmetals.
semiconductor
A substance that can conduct electric current under some conditions but not under other conditions.
dull / brittle
Solid nonmetals are _____ and _____ ?
group / properties
Elements of the same _____ share similar _____ ?
number of electrons in each atom
What information about each element is NOT provided by the periodic table?
a) number of electrons in each atom
b) atomic number
c) atomic mass
d) chemical symbol
Dalton's Atomic Theory
Who's theory? Atoms are like smooth, hard balls that could not be broken into smaller pieces.
7
How many periods in the periodic table?
18
How many groups in the periodic table?
Cloud Model
What theory? Electrons move rapidly with a cloud like region around the nucleus.
Thomson's Model
Who's theory? Suggested that atoms had negatively charged electrons set in a positive sphere.
Rutherford's Model
Who's theory? Suggested that the atom is mostly empt space but has a positive charge at its center.
Bohr's Model
Who's theory? Suggested that electrons move in specific orbits around the nucleus of and atom.