Transcript Atom - Cloudfront.net

What is an Atom?
• Atom: Smallest unit of
all matter
• 3 Main Parts:
– 1) Proton (+ charge)
– 2) Neutron (No charge)
– 3) Electron (- charge)
• Protons & Electrons
usually equal in number
• Elements (substance
made of only 1 type of
atom) are identified on
the Periodic Table
(page R36)
Reading the Periodic Table
• Atomic Number: Number • How many protons,
of protons (+) the atom
electrons, and neutrons
contains
does Carbon contain?
– Usually # of electrons also
• Atomic Mass: Combined
# of protons and neutrons
inside the nucleus
– Electrons too small to affect
mass
Protons = ______
Electrons = ______
Neutrons = ______
What’s the:
A) Atomic number of
Beryllium?
4
Atomic number =
Atomic mass =
Atomic number =
protons usually
amount of protons
amount of protons
same as electrons
+ neutrons
B) Atomic mass of Beryllium?
9
C) How many protons?
4
D) How many electrons?
4
E) How many neutrons?
5
• Electrons orbit the nucleus
in “energy levels”
1st level:
• closest to nucleus
• stable w/ 2 electrons
2nd level:
• stable w/ 8 electrons
3rd level:
• stable w/ 8 electrons
• Atoms are stable when the
outermost level is “full”
Examine Carbon below. It
has 2 electrons in the first
level and 4 electrons in the
2nd level. Is Carbon stable?
• Molecule: 2 or more atoms held
together by a covalent bond
– Form when atoms are
unstable
• Covalent Bond: Chemical bond
where atoms share electrons
– Ex: Oxygen (O2)
• Why unstable? Only 6
electrons in outer energy level
• What happens? Oxygen atom
will share two electrons with
their neighbor
• End result? Both end up with
8 electrons in its outer level to
become stable
sodium
chlorine
• Ionic bond: chemical bond where electrons are
gained/lost
– Creates Ions (atoms with + or – charge)
• Held together by magnetic attraction
• Cause: 1 atom steals an electron(s) from another atom
• Ex: Sodium + Chlorine = Sodium Chloride
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After bonding
Before bonding
Na
Cl
Protons
(+)
11+
17+
Electrons
(-)
11-
17-
Protons
(+)
Electrons
(-)
0
Net
charge
Net
charge
0
chlorine
sodium
ee
e
Na
Cl
11+
17+
10-
18-
+1
-1
Kobe Kuiz
1) Name the 3 subatomic particles.
2) Which subatomic particles are found inside the
nucleus?
3) The atomic number usually allows us to determine the
amount of which two subatomic particles?
4) If an atom has the atomic mass of 14 and the atomic
number of 6, how many protons, neutrons, and
electrons does the atom contain?
5) After an ionic bond is formed, what is the charge of
the atom that gained an electron?
6) Which type of chemical bond shares electrons?