smallest particle that can still be considered element
atom
Why did the atomic theory change within time?
As more evidence was collected more theories were made.
negatively charged particles set in a positive sphere
electrons
the specific amount of energy an electron has in it
energy level
the number of protons in the nucleus of an atom
atomic number
Dalton’s theory that atoms were small solid little balls that could not be broken into smaller pieces
the billiard ball theory
1897- Idea of a subatomic negatively charged particle (electron). Made Plum Pudding model of the atom.`
J.J. Thompson
from his gold foil expirments, he knew some substances give off + charged particles called alpha particles, most of the mass of an atom is in the nucleus, he reasoned that electrons in the atom are whirled around outside the nucleus, most of the atom is empty space
Ernest Rutherford
a Danish scientist created a new atomic model in 1913; described electrons as moving around the nucleus in fixed orbits and having a set amount of energy (planetary model)
Neils Bohr
Erwin Schrodinger’s atomic model; electrons in waves of probability
cloud theory
Discovered the neutron
James Chadwick
A subatomic particle that has no charge and that is found in the nucleus of an atom
neutron
Cloud vs. Bohr’s
Bohr said electrons orbit the nucleus like planets. Cloud says electron’s movement is related to its energy level. They move rapidly within a cloud-like region around the nucleus
a proton has a charge of ___?
+1
Electron has a charge of ___?
-1
What unit is used to describe the mass of an atom?
atomic mass unit
The atomic number of nitrogen is 7. How many protons, neutrons, and electrons make up an atom of nitrogen – 15
7 protons, 8 neutrons, and 7 electrons ****REMEMBER**** the atomic number is the number of protons.
the average mass of an of all the isotopes of that element
atomic mass
What did Mendeleev discover?
Mendeleev noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic number. He found that the properties repeated regularly. DEL ME
In what order did Mendeleev arrange the elements in his periodic table?
by increasing atomic mass
a one or two letter representation of an element
chemical symbol
What information does each periodic table contain?
In this book, the periodic table includes the atomic number, chemical symbol, name, and atomic mass for each element.
How is the Periodic table useful?
An element’s properties can be predicted from its location in the periodic table.
each vertical column of the periodic table
group
What do elements have in common in the same group?
They have similar characteristics.
a substance that can conduct electricity under some conditions
semiconductor
How did the Atomic theory Develop?
Atomic theory grew as a series of models that developed from experimental evidence. As more evidence was collected, the theory and models were revised.
the center of the atom which contains the protons and neutrons; a small region in an atom’s center where the atom’s positive charge is packed
nucleus
positively charged particles
protons
Describe the modern model of an atom.
At the center of the atom is a tiny, dense nucleus containing protons and neutrons. Surrounding the nucleus is a cloud-like region of moving electrons
atoms of the same element that differ in the number of neutrons they contain
isotopes
the sum of the number of neutrons and protons in an atomic nucleus
mass number
What did Mendeleev discover?
Mendeleev noticed that a pattern of properties appeared when he arranged the elements in the order of increasing atomic mass. He found that the properties of the elements repeated.
A table that shows the elements, their atomic number, symbol, and average atomic mass; elements with similar chemical properties are grouped together.
periodic table
What information does each periodic table contain?
The periodic table includes the atomic number, chemical symbol, name, and atomic mass for each element
horizontal rows in the periodic table
periods
How is the periodic table useful?
The properties of an element can be predicted from its location in the periodic table
have a shiny or metallic luster, good conductors of heat and electricity
metals
What are the properties of metals?
luster, malleability, ductility, and conductivity
the quality of giving off light, brightness, glitter, brilliance
luster
capable of being shaped
malleable
a term used to describe a material that can be pulled out into a long wire
ductile
the ability of a material to allow either heat or electricity to flow through it
conductivity
the ability of a substance to combine chemically with another substance
reactivity
The gradual wearing away of a metal element due to a chemical reaction
corrosion
How are metals classified?
In the periodic table, metals are classified as alkali metals, alkaline earth metals, transition metals, metals in mixed groups, lanthanides, and actinides.
Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density; Lithium, Sodium, Potassium, Rubidium, Cesium, Francium
alkali metals
metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive
alkaline earth metals
Groups 3-12, 1-2 electrons in the outer energy level, less reactive than alkali-earth metals, shiny, good conductor of thermal energy and electrical current, high density
transition metals
an element that lacks most of the properties of a metal
nonmetal
What are the properties of nonmetals?
In general, most nonmetals are poor conductors of electric and heat. Solid nonmetals tend to be dull and brittle
What are the families containing nonmetals
The families containing nonmetals include the carbon family, the nitrogen family, the oxygen family, the halogen family, the noble gases, and hydrogen
a molecule consisting of two atoms
diatomic molecule
group 17; contains nonmetals; 7 electrons in its outermost energy level; very reactive; poor conductors of electric current; never in its uncombined form in nature; combine with most metals to form salts
halogens
one of the elements of group 18 of the periodic table(helium, neon,argon, krypton, xenon, and radon); noble gases are nonreactive
noble gases
elements that have characteristics of metals and nonmetals
metalloids
