Download Dissecting Atoms

Dissecting Atoms
3 subatomic particles
Protons, neutrons, electrons
Subatomic particle properties
• Protons have a mass of ___________, a charge of
_________ and are found in the __________
• 1 AMU (Atomic Mass Unit), +1, nucleus
• Neutrons have a mass of __________, a charge of
_________ and are found in the __________
• 1 AMU (Atomic Mass Unit), 0, nucleus
• Electrons have negligible mass, or _________, a charge of
________ and are found in the ______________________
• ~0 AMU, -1, electron cloud around nucleus.
• Therefore, the mass of an atom (or, atomic mass) is equal
to ____________ + ______________.
• # of protons + # of neutrons
• Average atomic mass = weighted average of all isotopes of
element
Periodic table of elements
•
•
•
•
A Atomic # = # of Protons
B atomic mass
C Element Symbol
D Element Name
Isotopes
• Isotopes of an element have different
numbers of ____________________
• neutrons
• All isotopes of an element have the same
chemical properties.
Atomic Charge
• Since an electron has a charge of ___________ and a proton has a
charge of __________, when you add electrons and protons
together, they cancel each other out. +3 +(-3)=0.
• -1 , +1
• Thus, 3 protons plus 3 electrons = 0 charge. This is called
_____________.
• neutral
• If you have more electrons than protons, the atom’s charge will be
negative/positive (circle one).
• negative
• If you have more protons than electrons, the atom’s charge will be
negative/positive (circle one).
• positive
If you change the number of ________,
you change the ____________
• If you change the number of protons, you
change the
• element
• If you change the number of neutrons, you
change the
• Atomic mass, isotope number
• If you change the number of electrons, you
change the
• Charge, reactivity of atom
Large vs. Small Atoms
• Large/small (circle one) atoms are more
stable
• Small
• Larger atoms tend to be more radioactive
(losing parts from the nucleus)
Chemical Bonds
• _________ determine the reactivity of an
atom
• Number of electrons in outer shell
Ionic Bonding
• When atoms give electrons away, their charge
becomes ____
• Positive (because there are now more protons than
electrons)
• When atoms receive extra electrons, their charge
becomes___
• Negative
• Oppositely charge atoms are attracted to each other.
So they stick together. This is called an ___ bond.
• ionic
Ionic Bonding
Covalent Bonding
CH4, Methane
• When atoms share electrons.
This is called a ___ bond.
• Covalent
• ____ is an example of covalent
bonding.
• Water, H2O
• The term used for two or
more covalently bonded
atoms is…
• Molecule
Water
• Water has ____ bonding
• Covalent
• Water’s chemical formula is __.
This means it has ___ H’s and ___
O’s.
• H2O, 2, 1
• H stands ____. It has ___ proton,
and __ electron.
• hydrogen, 1, 1
• O stands for ___. It has ___
protons and ___ electrons.
• oxygen, 8, 8
Water’s Polarity
• …this makes the oxygen side of the molecule more ___
charged, and the hydrogen side more ___ charged.
• Negatively, positively
• When one side of a molecule has a slightly different
charge than the other, it is said to be ___.
• Polar
Hydrogen Bonding
• The polarity of water makes it so
that the negatively charged ends
of a molecule are attracted to the
___ charged ends of the nearby
water molecules. Due to this
attraction, they form weak ___
bonds.
• positively, hydrogen
Hydrogen Bonding
• Water floats when it ___ because the
molecules slow down enough for the
hydrogen bonds to keep the molecules in a
fixed lattice position with respect to each
other. This leaves space between the
molecules (so, less dense).
• freezes
Why frozen water floats…
PLAY
THIS

https://www.youtube.com/watch?v=T4GCShGvw-M#t=150.836824
Review
• If water boils at ____ °C (212 °F) and freezes at ____ °C
(32 °F),
• 100, 0
• Then explain why water is most dense at 4 °C
• As temp drops, molecule movement slows, bringing
them closer together
• At 4 °C, molecules slow so much that the hydrogen
bonds take over and fix them into place with regard to
each other, spreading them back out again,
• Making ice _____ dense than liquid water
Importance to Life of
Ice Floating
1. Aquatic creatures would get crushed if ice
sank (like in lakes and streams)
2. The ice forms an insulating layer between the
air temp, which can get very cold, and the
water beneath
PLAY
THIS

https://www.youtube.com/watch?v=UukRgqzk-KE
Hydrogen bonding
• ___ is the attraction water molecules
have for each other.
• ___ is the attraction water molecules
have for other surfaces, due to
polarity.
Capillary Action
• how even the tallest trees get
water from their roots to their
leaves
•
https://www.youtube.com/watch?v=vNCH6uhB_Bs
• adhesion makes water “stick” to
the sides of the tube, and “climb”
up
• cohesion keeps the water column
together as it rises
• the smaller the tube diameter, the
higher the water column rises
humans
•
https://www.youtube.com/watch?v=VXo-wLR8Aic stop at math
•
https://www.youtube.com/watch?v=BickMFHAZR0
Surface Tension
• Surface tension – cohesion between water
molecules causes them to hold together and
allows very light objects to stay on the surface
• http://video.nationalgeographic.com/video/deadli
est-jesus-christ-lizard
Water is Universal Solvent
– Due to its polarity, almost everything dissolves in water…
almost
– Substances that are dissolved by water are also polar, so
water’s negative and positive poles can pull on their own
negative and positive ends, and pull them apart
– Polar substances are hydrophilic (water loving)
– fats, oils and waxes are hydrophobic (water afraid), and
non-polar. They do NOT dissolve in water.
– Water beads on a freshly waxed car because the wax is
hydrophobic to the water. There is no adhesion between
them.
Properties of Water Review videos
• Amoeba sisters review:
https://www.youtube.com/watch?v=3jwAGWky98c
• Hank Green Crash Course Water
• https://www.youtube.com/watch?v=HVT3Y3_gHGg
• Bozeman Science properties of water
• https://www.youtube.com/watch?v=iOOvX0jmhJ4
Acids and Bases
• topics
–
–
–
–
–
–
–
–
–
–
–
pH scale
Logarithmic scale
Water dissociation
H+ and OH- ions
Typical acids and bases and their properties
TED ed on acids and bases
https://www.youtube.com/watch?v=DupXDD87oHc
Paul Anderson: Bozeman Science Acids and Bases
https://www.youtube.com/watch?v=Xeuyc55LqiY
(older version :
https://www.youtube.com/watch?v=DupXDD87oHc
Mixtures, Solutions and
Suspensions
Mixtures
• 2 or more substances combined physically, but not
chemically
• Mixtures can be dry, like salt and pepper
• Or gas, like air
• Or wet
• (like substances dissolved in water)
• The two types of wet mixtures are solutions and
suspensions
• So, all solutions and suspensions are also mixtures
• But, not all mixtures are solutions or suspensions
solutions
• One substance dissolved into the other
• Solute – gets dissolved (like sugar in hot tea)
• Solvent – does the dissolving
– often, the solvent is water
Tea solution with ice MIXed in
suspension
• Mixture of water and nondissolved material
• The material is inside the water,
not sunken or floating
Mixture, solution or suspension?
• Coffee with cream
– Mixture & solution
• Coke
– Mixture and solution
• Layered cake
– mixture
• Toothpaste with whitening flecks
– Mixture, &
– Solution (toothpaste is a very thick liquid & stuff is dissolved in
the paste), &
– Suspension (some stuff isn’t dissolved)
• Sweet iced tea
– Mixture, solution & suspension