Atoms
neutrons
- particles located in the nucleus of an atom that have NO charge - mass = 1 amu
Why are diamonds and graphite so different if they both are made of the same atom (carbon)?
The carbon atoms are arranged differently.
Which subatomic particle determines an atom's reactivity?
The electron arrangement determines reactivity, specifically the number of electrons in the outer energy level
The further apart the charges are, the _______________ the force of attraction or repulsion is between them.
weaker
protons
- POSITIVELY charge particles located in the nucleus of an atom - mass = 1 amu
nucleus
- dense, central part of the atom - composed of protons and neutrons
electrons
-NEGATIVELY charge particles located OUTSIDE the nucleus in electron clouds - mass = so tiny (almost zero)
Most atoms (those with two or more energy levels) will react with other atoms to achieve ___________ valence electrons.
8
reactivity
A measure of how readily a substance combines chemically with other substances.
Periodic Table
A table that shows all the known elements, their atomic number, symbol, and average atomic mass; elements with similar chemical properties are grouped together.
How do you find the number of neutrons in the nucleus of an atom?
Subtract the atomic number from the mass number Mass # - Atomic # = number of neutrons
Why are atoms neutral?
The # of protons equals the # of electrons
If the nucleus was the size of a grape, the electrons would be almost a mile away! What does this tell us about the atom?
The atom is mostly empty space.
Which subatomic particle determines an atom's identity?
The number of protons determines the identity of an atom. Ex: all atoms with 6 protons are carbon atoms; all atoms with 20 protons are calcium atoms
Protons repel each other in the nucleus. What holds the nucleus together?
The strong force
What do diamond and graphite both have in common?
They are both are made of pure carbon atoms.
Noble Gases (Group 18)
an unreactive family on the Periodic Table; all members of this family have 8 electrons in the outer energy level with the exception of helium. Helium is unreactive because it has only one energy level which is filled with 2 electrons (the maximum number for the first energy level).
Opposite charges ___________.
attract each other
valence electrons
electrons in the outermost energy level of an atom
The closer the charges are, the _______________ the force of attraction or repulsion is between them.
greater
inert
nonreactive
What is the charge of the nucleus?
positive - due to the presence of protons
Argon: Atomic # 18 Atomic Mass: 39.948 Determine the number of protons, neutrons and electrons in an atom of argon.
protons: 18 neutrons: 22 (40-18) electrons: 18
Copper: Atomic #: 29 Atomic Mass: 63.546 Determine the number of protons, neutrons and electrons in a copper atom.
protons: 29 neutrons: 35 (64- 29) electrons: 29
Zinc: Atomic #: 30 Atomic Mass: 65.39 Determine the number of protons, neutrons and electrons in a zinc atom.
protons: 30 neutrons: 35 (64-30) electrons: 30
Like charges __________.
repel each other
Why is the overall charge of an atom neutral?
same amount of protons and electrons
Atom
smallest particle of an element (the building block of matter)
Where does the majority of an atom's mass exist?
the nucleus
atomic number
the number of protons in the nucleus of an atom
subatomic particles
the smaller particles (protons, neutrons & electrons) that make up an atom
mass number
the sum of the protons and neutrons in the nucleus of an atom
What is the mass number of a sulfur atom that contains 16 protons, 16 neutrons and 16 electrons?
Mass # = 32 (16 protons + 16 neutrons)
If an element has 79 protons, 118 neutrons and 79 electrons, what is its atomic number?
Atomic # = 79 (Atomic # = # of protons)
What is the difference between atomic mass and mass number?
Atomic mass is the weighted average of the masses of all of the isotopes of an element. Mass number is the sum of the protons and neutrons for a given atom. (It is NOT an average.)
How will atoms achieve a stable number of valence electrons?
Atoms can GAIN, LOSE or SHARE valence electrons to get the stable number (8 - for most atoms) in their outer energy level.
Isotopes
Atoms of the same element that differ in the number of neutrons. For example, carbon-12 and carbon-13 both have 6 protons, but carbon-12 has 6 neutrons and carbon- 13 has 7 neutrons.