Warm Up
9-1-15
1. Classify the following as pure substance or
mixture: kool aid, tap water, air, sugar packet
2. What kind of pure substance is NaCl?
3. Name the two types of mixtures.
4. An object has a density of 4 g/cm3 and a
volume of 8 cm3, find its mass.
Agenda
Homework
Turn in Test Review worksheet
Go over quiz
Notes Unit 2-1
Lab Density Engineering
Test Unit 1 + Notebook Check
Quiz Unit 1
• Version 1
1. 0.03652 kg
2. 2396 cm
3. 0.33 cm3 or 0.25 cm3
4. 180 g
5. When mixing different
substances but they do
not mix and result in
layers. Ex. Cereal and
milk
6. Bubbles, color change,
temperature change,
precipitate (forming
solids particles
• Version 2
1. 6.53 kg
2. 6.39 cm
3. 0.5 cm3
4. 80 g
5. When mixing different
substances and they mix
thoroughly resulting in
only 1 layer. Ex. Sugar in
water
6. Bubbles, color change,
temperature change,
precipitate (forming
solids particles
Unit 2-1
Substances Are Made of Atoms
Atomic Theory
• States that atoms are building blocks of all
matter.
• Three laws that support the current atomic
theory
Atomic Theory
Current Model
Electron cloud instead of orbital
The atom model will change when new/better data come out
Atomic Theory
• Law of definite proportions - chemical
compound always contain the same elements in
the exact same proportions by mass.
Oxygen
Carbon
Hydrogen
C2H6O2
Atomic Theory
• Law of conservation of mass – mass cannot be
created or destroyed. Mass in reactants equal
the mass in products.
baking
soda
CO2 gas
vinegar
solution
Sodium
bicarbonate +
2 grams
acetic
acid
2 grams
-------->
carbon
dioxide
+
4 grams total
Sodium
acetate
and water
sodium
acetate
+
H 2O
Atomic Theory
• Law of multiple proportions - the masses of
one element which combine with a fixed mass
of the second element, are in a ratio of whole
numbers.
Chemical Name
Nitrogen monoxide
Nitrogen dioxide
Nitrous oxide
Water
Hydrogen peroxide
Formula
NO
NO2
N2O
H2O
H2O2
Ratio
1:1
1:2
2:1
2:1
1:1
Atomic Theory
• Elements combine in whole numbers
Dalton’s Atomic Theory
• 1808 – John Dalton combined the three laws
and revised the early Greek idea of atoms
• Part of his theory are
incorrect by today’s
standards because of
our technology
Dalton’s Atomic Theory
1. Matter is made of atoms, which cannot be
subdivided into smaller components
2. Atoms of a element are identical in their
physical and chemical properties
3. Atoms of different elements differ in their
physical and chemical properties
4. Atoms combine in simple, whole-number
ratios to form compounds
5. Atoms are rearrange in a reaction but not
created, destroyed or changed (transformed)
Engineering Challenge
• Density and Archimedes’ Principle
-Create a boat to hold as much pennies as
possible without sinking
Assignments
Notebook checklist
• 5 days of notes = 25 points
– Warm ups - questions/answers/date
– Notes - Cornell format
– Summary with signature
Online homework
• Extended till 9PM tonight