Transcript Chemistry

Which project is most likely to interest a
scientist working at a biotechnology company?
A
development of genetically modified corn
plants
 B study and reconstruction of fossilized
bones
 C conservation of key species within
ecosystems
 D prevention of sewage leaking into water
supplies
A
very small piece of matter
 Made up of…
 3 different types of particles
 Electrons (negative charge)
 Protons (positive charge)
 Neutrons (no charge)
Particles of matter
- Atoms
- Molecules
- Macromolecules
- Cell organelles
- Cells
- Tissues
- Organs
- Systems
- Organisms
- Populations
- Ecosystems
- Biospheres
- Planets
- Planetary Systems with Stars
- Galaxies
- The Universe
A
type of atom with a unique set of
characteristics
 Each has a unique atomic number ( # of
protons)
 There are ~120 known elements
 Examples?
 If
you read a book, you will find a bunch of
words on a page. Letters make up those
words. In English, we only have twenty-six
letters, but we can make thousands of
words. In chemistry, you are working with
around 120 elements, and when you combine
them you can make millions of molecules.
Molecules are groups of atoms bonded
together in the same way that words are
groups of letters. An "A" will always be an "A"
no matter what word it is in. A sodium (Na)
atom will always be a sodium atom no
matter what compound it is in.
 http://education.jlab.org/elementmath/
 Multiple
atoms joined together
 Can be the same type of atoms or different
types
 Examples?
Dihydrogen monoxide
C8H10N4O2
A
molecule made up of at least 2 different
elements
 Has a fixed ratio determining the composition
2 atoms of hydrogen + 1 atom of oxygen
becomes 1 molecule of a compound: water
 1.
Table Salt (Sodium Chloride)- NaCl
 2. Sugar (Sucrose)- C12H22O11
 3. Hydrochloric Acid (Muriatic Acid)- HCl
 4. Vitamin C (Ascorbic Acid)- C6H8O6
 5. Aspirin (Acetylsalicylic Acid)- C9H8O4
 6. Ammonia- NH3
 7. Rubbing Alcohol (Ethanol)- C2H5OH
 8. Baking Soda (Sodium Bicarbonate)NaHCO3
 9. Mothballs (Naphthalene)- C10H8
 This
A. 5
B. 11
C. 22
D. 23
element has ___ protons.
In a food pyramid which best explains why the
number of organisms decreases from 1 trophic
level to the next?
 A. consumers at the lower level require more
energy than the upper level consumers
 B. consumers at the top level require more
energy than the lower level consumers
 C. the consumers are feeding on larger
organisms that have less energy
 D. the consumers are feeding on smaller
organisms that have less energy
 Does
not change what is in an molecule
 Changes how molecules are connected- phase or
shape (vaporization, condensation, sublimation)
 Examples…
 Crushing, melting, breaking, chopping,
shredding, freezing
 Usually reversible
 Changes
what is in a molecule
 Makes a substance that wasn't there before
 Look for clues a chemical reaction took
place: light, heat, color change, gas
production, odor, or sound
 Which
of these best defines a chemical
change?
 A. a change that can be reversed
 B. a change that can not be reversed
 C. a change that can sometimes be reversed
 D. a change that causes a reaction
 2+
substances which have been combined so
that each substance retains its own chemical
identity
 can be separated from each other by physical
means (filtration/distillation )
 Examples: rocks, air, crude oil (unrefined
petroleum), sea water, and steel
 The
components are completely and evenly
mixed with one another, all parts are identical
 Example : salt water, fruit punch, stainless
steel, air
 Unevenly
combined mixtures, all parts not
the same (If you take one sample of a
heterogeneous mixture and another sample
from a different part of the mixture, the two
won’t be identical to one another)
 Examples : food, soil, mixtures with visually
different components
2
2.
1.
3.
4.
5.
 Which
of the following is an example of
physical change?
Mixing baking soda and vinegar together, and
this causes bubbles and foam.
 A glass cup falls from the counter and shatters
on the ground.
 Lighting a piece of paper on fire and the paper
burns up and leaves ashes.
 Baking a birthday cake for your mother.

 Which
of the following is an example of
chemical change?




Filling up a balloon with hot air.
Taking a glass of water and freezing it by
placing it in the freezer.
A plant collecting sunlight and turning it into
food.
Your dog ripping up your homework.
 If
the chemical properties of a substance
remain unchanged and the appearance or
shape of an substance changes it is called a




Chemical change
Physical change
Both a physical and chemical change
Neither a physical or chemical change
 What
characteristic best describes what
happen during a physical change?




Composition changes
Composition stays the same
Form stays the same
Mass is lost
 Which




is an example of chemical change?
Water freezes
Wood is cut
Bread is baked
Wire is bent
 Which
is not a clue that could indicate a
chemical change?




Change in color
Change in shape
Change in energy
Change in odor
 Electrons
exist in layers called shells
 Outermost electron = valence electron
 Ununseptium 2, 8, 18, 32, 32, 18, 7
 It is possible to create ions (charged atoms)
by “stealing” valence electrons
 Set
up according to element reactivity
 Periods
 Group
 Period
= across
Groups = up/down
indicates the # of valence e-
indicates the # of shells
 All
of the elements in a period have the same
number of atomic orbitals. Every element in the
top row (the first period) has one orbital for its
electrons. All of the elements in the second row
(the second period) have two orbitals for their
electrons. It goes down the periodic table like
that. At this time, the maximum number of
electron orbitals or electron shells for any element
is seven.

 Draw
an atom of Na, Cl, and B, and O
 Include
1. atomic number
2. # of electrons
3. Clearly drawn electron shells and
nucleus
4. Calculate the ionic charge
5. Explain why it is in the group that it is
6. Explain why it is in the period that it is
7. Is the atom more likely to gain or lose e-
 1.
malleable – squishes but doesn’t break
 2. shiny – reflective, bright
 3. ductile – can be made into wires
 4. good conductors (carriers) of electricity
and heat
 Metals
– easily lose electrons, shiny,
malleable, easily conducts electricity
 Non Metals – dull, don’t easily conduct
electricity,
 Metalloids - have properties of both metals
and nonmetals
 Chemical
Bond = interaction that holds 2
atoms together
 An atom either 1. loses e- 2. gains e- 3.
shares e Only involves the valence e-
 Ion
= atom or molecule with a charge
 Ionic ( between ions) : the e- is transferred
 Covalent : the e- is shared
 Break down “covalent”
 Polar
– having two poles ( of electrical
charge)
 Polarity – when something is polar it has this
 Bonds and molecules can be polar
 This happens because of electronegativity
 Electronegativity – how much an atom wants
to gain electrons
 The
way combining atoms is written out
 Have arrows that mean….
 A chemical change has occurred
 Products ( on the right of arrow)
 Reactants ( left of arrow)
 H2 +
o2  H2o
 C2H6O
+ O2 -----> CO2 + H2O
Chemical
Symbol
Meaning
Composition
H2O
One molecule
of water:
2 H2O
Two molecules
of water:
Four H atoms and two O atoms
One molecule
of hydrogen
peroxide:
Two H atoms and two O atoms
H2O2
Two H atoms and one O atom
 The
law says that….
 …matter cannot be created or destroyed
 What does this have to do with chemistry??
 Chemical equations will be balanced
Unbalanced and Balanced Equations
H
Cl
Cl
H
H
H
H
Cl
H2 + Cl2  HCl (unbalanced)
reactants
H
Cl
2
2
H
H
Cl
Cl
Cl
H2 + Cl2  2 HCl (balanced)
reactants
products
1
1
Cl
H
Cl
2
2
products
2
2