Seconds 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.

Seconds Left: 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.

Seconds Left: Describe the difference between a mixture and a compound.

Compounds are chemically combined, mixtures are not.

Seconds Left: Define: Solute Solvent Solution

Solution – homogeneous mixture where a solute is dissolved in a solvent Solute – the matter that gets dissolved Solvent – the matter that does the dissolving

This screen will disappear in 3 minutes. Seconds Remaining. Propane has three atoms of carbon and eight atoms of hydrogen. What is propane's chemical formula?

C3H8C3H8

This screen will disappear in 3 minutes. Seconds Remaining. Which kind of mixture is sometimes difficult to distinguish from a compound? Why?

Homogeneous mixtures because the mixtures are the same throughout

This screen will disappear in 3 minutes. Seconds Remaining. 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

Seconds left: 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.

You have Seconds left. 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.

Time left:Seconds Define these terms: Atom Isotope Ion

ATOM – the smallest part of matter that has the properties of the matter ISOTOPE – different forms of the same atom; they have the same numbers of protons, but different numbers of neutrons ION – an atom that has lost or gained electrons

Seconds Remaining: Define the terms: Element Mixture Compound Molecule

ELEMENT – matter made of only one type of atom; a pure substance MIXTURE – a combination of different types of matter in no fixed proportion; can be physically taken apart COMPOUND – a combination of different types of matter in specific proportions; must be chemically taken apart MOLECULE – the smallest part of a compound that has all the properties of that compound

Seconds Remaining: 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.

Seconds Remaining: 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, was observed forming. Because it is different in 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.

Seconds left: 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

Seconds Remaining: 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

Seconds Remaining: Describe the difference between ionic and covalent bonding.

Ionic bonding is the gaining or losing of electrons in atoms to make happy atoms. Covalent bonding is the sharing of electrons between atoms to make happy atoms.

Seconds Remaining: Which group of elements on the periodic table does not readily combine with other elements ?

Group 18 - the Noble Gasses

Seconds Remaining: List the elements in this compound: H 2 SO 4 How many atoms of each element are in the compound?

H 2 SO 4 Hydrogen – 2 atoms Sulfur – 1 atom Oxygen – 4 atoms

Seconds Left: 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

SecondsRemaining: What are the biggest parts of an atom ?

Protons & Neutrons

SECONDS REMAINING: 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.

SECONDS REMAINING: 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.

Seconds Remaining: State the Law of Conservation of Mass

Matter cannot be created or destroyed in an ordinary chemical reaction.

Seconds Remaining: 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.

Seconds Remaining: Describe endothermic and exothermic

Endothermic – absorbing energy Exothermic – releasing energy

Seconds Remaining: A student wrote the following equation: 4Al + 3O 2 2Al 2 O 3 – Write a sentence to describe what occurs in this reaction.

In this reaction, aluminum reacts with oxygen to form Al 2 O 3.

Seconds Left: 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” 3H 2 SO 4 = H 2 SO 4 6 – H, 3 – S, H 2 SO 4 = 2 – hydrogen 1 – Sulfur 4 – Oxygen coefficient subscript

Seconds Left: Describe metalloids.

Elements having properties of both metals and nonmetals.

Seconds Left: 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.

SECONDS LEFT: 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

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.

Seconds Remaining: Identify the reactants, products, subscripts, and coefficients in this chemical equation: 6 CO H 2 O + light → C 6 H 12 O O 2

Coefficients Subscripts Carbon Dioxide + Water + Light energy → Glucose + Oxygen Reactants: CO 2 H 2 O light Products: C 6 H 12 O 6 O2

Time Remaining: 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

Seconds Left: 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

Seconds Left: 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.

Seconds Left: 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.