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1801701601501401301201101009080706050403020109876543210Seconds Left:
A stable carbon atom has the following parts:
– 6 protons
– 6 neutrons
– 6 electrons
Describe the location of each of these parts in a carbon atom.
Protons and neutrons are found in the nucleus of the atom, at the very center. Electrons are
found in an electron cloud that surrounds the nucleus.
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If there only about 100 types of elements in the world, why are there so many
different kinds of matter?
Elements can combine in many different ways to form many
different types of matter.
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Describe the difference between a mixture and a
compound.
Compounds are chemically combined, mixtures are not.
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Propane has three atoms of carbon and
eight atoms of hydrogen. What is propane's chemical
formula?
C3H8
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Describe the three kinds of particles found in atoms.
Where are they located & what are their charges?
• Protons – in the nucleus, positive charge• Neutrons – in the nucleus, no charge• Electrons – outside the nucleus,
negative charge
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An electrically neutral atom undergoes a change to become negatively charged. The atom's atomic mass decreases. A student explains that the atom most
likely lost a neutron.
– Describe one strength and one weakness of the student's explanation.
One strength of the explanation is that an atom's mass consists mostly of the mass of its protons and neutrons. Electrons have very little mass. So, the atom must have lost either a proton or
neutron.
One weakness, however, is that neutrons have no charge. So, removing the neutron should not affect the atom's charge. It is more likely
that a proton was removed.
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Draw the Diagram
–Identify the four parts of the atom that are pointed out by arrows in the diagram above.
–Describe the electrical charges of the structures that are labeled 1, 2, and 3 in the diagram.
Number 1 is the electron, 2 is the proton, 3 is the neutron, and 4 is the nucleus. The electron is
negative. The proton is positive. The neutron is neutral.
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Define these terms:
Atom
Element
ATOM – the smallest part of matter that has the properties of the matter
ELEMENT – matter made of only one type of atom; a pure substance
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Define the terms:
Mixture
Compound
Molecule
MIXTURE – a combination of different types of matter in no fixed proportion; can be physically taken apart
physical change
COMPOUND – a combination of different types of matter in specific proportions; must be chemically taken apart
chemical change
MOLECULE – the smallest part of a compound that has all the properties of that compound
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Many chemical reactions occur around the home.
– Describe one chemical reaction that occurs in a home and the
products of the reaction.
A chemical reaction that occurs around the home is the burning of charcoal for barbecues. When
charcoal burns, it reacts with oxygen to form ash, carbon dioxide, and heat.
The cooking of food is another example.
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List the four signs of a chemical reaction
1. Formation of a gas
2. Formation of a precipitate (solid in a liquid)
3. Color change
4. Energy change
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Copper sulfate, when dissolved in water, has a blue color. When steel wool is mixed
with a copper sulfate solution, the steel wool disappears, a brownish solid forms,
and the color of the solution changes from blue to green.
– Explain how three changes that occur in this experiment suggest a new
substance may have been formed.
The disappearance of the steel wool suggests that a new substance is forming. As steel does not dissolve in water, it is likely that it was part of the reaction that formed a new
substance. Another new substance, the brown solid(precipitate), was observed
forming. It is a different color from the other substances, it is also probably a new
substance. The color change of the solution from blue to green implies that a chemical
change has taken place.
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Where are the metals, nonmetals, and metalloids
located in the periodic table?
• Metals - are on the left side• Nonmetals – are on the right side• Metalloids – are on a slanting line
between the metals and nonmetals (zigzag) (stairstep)
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Which group of elements on the periodic table does not readily combine with other elements?
Group 18 - the Noble Gasses
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List the elements in this compound: H2SO4
How many atoms of each element are in the compound?
H2SO4
Hydrogen – 2 atoms
Sulfur – 1 atom
Oxygen – 4 atoms
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What are the biggest parts of an atom?
Protons & Neutrons
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What happens to atoms during a chemical
reaction?
Chemical reactions occur when different atoms and molecules combine together and spit
apart.
Atoms are re-arranged in the way they are connected (or bonded); they are not created or
destroyed.
Law of Conservation of Mass
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Explain the difference between chemical and
physical changes.
PHYSICAL REACTION – is a change that affects the size, shape or color of a substance but does not affect its composition – no new substance is formed
Examples might by melting, boiling, cutting, etc.
CHEMICAL REACTION – is a change caused by the rearrangement of the atoms of one or more substances, resulting in the formation of new substances, having entirely different properties.
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State the Law of Conservation of Mass
Matter cannot be created or destroyed in an ordinary chemical reaction.
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What does a chemical equation
tell us?
Chemical equations tell us how many atoms or molecules react with each other and how much
of a substance is needed to react properly with another.
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Describe endothermic and exothermic
Endothermic – absorbing energy(cold)
Exothermic – releasing energy(hot)
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A student wrote the following equation:
4Al + 3O2 2Al2O3
– Write a sentence to describe what occurs in this reaction.
In this reaction, 4 aluminum reacts with 6 oxygen to form 2Al2O3.
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What do coefficients & subscripts show us in chemical formulas?
Coefficients – the number of
molecules
Subscripts – the number of atoms
No number is understood to be “1”
3H2SO4 =
H2SO4
H2SO4
H2SO4
6 – H, 3 – S, 12 - O
H2SO4 =
2 – hydrogen
1 – Sulfur
4 – Oxygen coefficient
subscript
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Describe metalloids.
Elements having properties of both metals and nonmetals.
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Students carry out a chemical reaction by mixing two solutions in a glass beaker. A temperature
probe in the beaker records changes in temperature that occur after mixing. Within
seconds after mixing, the temperature rises from 25 °C to 40 °C. Then the temperature returns to 25
°C over a period of several minutes.
–Based on this data, what should be concluded about the type of chemical reaction that has
occurred?
The best conclusion is that an exothermic reaction has occurred. The students
observe the temperature rising by 15 °C soon after they mix the chemicals. This shows that the reaction has given off
energy as heat. Although there is cooling afterward, that is normal. Any hot object
cools as it gives off heat.
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The table to the left shows the melting points for some
minerals.
A student considers making either a line graph or a circle
graph to show this data.
– Evaluate how well each type of graph would communicate the
data in the table.
Mineral Melting Points
Mineral Melting Points
A line graph would be a bad choice for showing this data. The data does not have pairs of
numbers that could be plotted on a grid. Also, there is no trend that could be shown by a line.
A circle graph is also a bad choice. The data are melting points for different minerals. They are not parts of one thing. So, a circle graph
would not make sense.
What graph would work the best?
BAR GRAPH
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Identify the reactants, products, subscripts, and coefficients in this chemical equation:
6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
6 CO2 + 6 H2O + light → C6H12O6 + 6 O2
CoefficientsSubscripts
Carbon Dioxide + Water + Light energy → Glucose + Oxygen
Reactants:
6CO2
6H2Olight
Products:
C6H12O6
6O2
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Betsy mixes and stirs two chemical solids together. While stirring she
notices that the beaker is getting hot. What is happening to the beaker?
The reaction of the two chemicals is releasing heat – an EXOTHERMIC
reaction
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A stable helium atom contains 2 protons, 2 neutrons, and 2 electrons.
– Draw and label a diagram of a stable helium atom. Be sure to include the
protons, neutrons, electrons, and nucleus
of the atom in your diagram.
Helium Atom
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Germanium, with an atomic number of 32, is not a metal or a non-metal, but a metalloid.
– Describe where metalloids are found on the periodic table, with respect to the metals
and non-metals.
Metalloids are found in between metals and non-metals on the periodic table. Their position
tells us that they have some of the characteristics of metals and some
characteristics of non-metals. For example, germanium conducts electricity, but not as well
as true metals.
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Elements are organized in the periodic table in such a way that there are patterns of elements
placed close together that have similar properties. For example, knowing the properties of one
element in a column of the periodic table will help a person predict the properties of other elements
in that same column.–Describe two properties common to elements
found at the far left of the periodic table.–Describe two properties common to elements
found at the far right of the periodic table.
On the far left side of the periodic table the elements are all metals. So, they are
solids at room temperature and are good conductors of heat and electricity.
One the far right side of the periodic table, the elements are gases at room temperature. They are colorless and
non-reactive.
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An atom consists of 7 neutrons, 7 electrons, and a number of protons.
The atom has a charge of -1. What is its mass number?
The atom has a mass number of 13• To find the mass number we have to know
the # of protons & the # of neutrons.– We know there are 7 neutrons; ??? protons
• An atom with a charge of -1 has gained an electron (added a – charge)
• Atoms begin w/ = numbers of protons & electrons, so the atom began with 6 electrons & 6 protons.
• 6 protons + 7 neutrons = • a mass # of 13