1. TAKS objective 3 Structure and Properties of Matter
Middle School Science
Science TAKS Need to Know
TAKS Need to Know

2. Atomic Theory Atoms are building blocks of elements
Atoms in each unique element are the same (Ex: Every oxygen element has the same # of protons)
Atoms are different from atoms of other elements (Ex: Hydrogen has a different # of protons than oxygen)
Two or more different atoms bond in simple ratios to form compounds (Ex: Hydrogen & oxygen can chemically combine to form water- H2O )
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3. solid liquid gas TAKS Need to Know
gas
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5. Atoms and Elements
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6. Atomic Particle Charges
Protons Positive +
Neutrons Neutral =
Electrons Negative -
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7. Location of Subatomic Particles
10-13 cm
electrons
protons
neutrons
10-8 cm
nucleus
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8. Location of Atomic Particles
Inside the Nucleus
Protons with a Positive charge
AND
Neutrons with a Neutral charge –that means they do not have a charge
Outside the Nucleus- in electron cloud
Electrons with a Negative charge
Did you know electrons are very, very small and move very, very fast???
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9. Periodic Squares 11 Na
22.99
The periodic square for an element can tell you lots of information about that atom.
Atomic number = # of protons
Atomic number = # of electrons
That means in a neutral (uncharged) atom the # of protons and electrons are always the SAME!!!!
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10. Atomic Mass on the Periodic Table
Atomic Number
or Protons 11 Na
22.99
Symbol
Atomic Mass or
Protons + neutrons
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11. Atomic Number
Atomic number =
# of Protons
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12. The number of protons and neutrons in an atom Mass Number
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13. Number of Electrons A balanced atom is neutral
The net overall charge is zero
Number of protons = Number of electrons
Atomic number = Number of electrons
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17. The stair-step line separates the elements into metals and nonmetals.
Elements with similar properties are placed in the same group in the periodic table.
The stair-step line separates the elements into metals and nonmetals.
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18. Metals & Nonmetals
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19. 2 elements with similar properties
Protons
Neutrons
Electrons
2 elements with similar properties
Chlorine-35 17 18
F and Br
Iron-56
Magnesium-24
Lead-208
Nitrogen-14 26 30 26
Ru and Os 12 12 12
Ca and Sr
126 82 82
Sn and Ge 7 7 7
P and As
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20. Specific Heat
Measure of how much heat matter can absorb. It is a measure of how much heat energy it takes to make 1 gram of a substance rise 1o C in temperature.
Heat is measured in calories.
A calorie is the amount of heat needed to make 1 g of water rise 1o C in temperature.
The higher a substance’s specific heat, the harder it is to increase its temperature (as with the cloth car seat). The opposite is also true: a substance with lower specific heat increases in temperature very easily (as with the metal car door).
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22. If you want to keep the temperature of something from changing very much…build it out of a material that has a high specific heat.
Most metals have low specific heats, while nonmetal compounds & mixtures such as water, wood, soil, & air have relatively high specific heats.
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23. How the Specific Heat of Water affects the Earth
Oceans cover about 2/3 of Earth’s surface. Water’s characteristic of retaining heat is important to our climate.
It means that our climate stays much more stable than it would if there were less water on Earth.
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24. Molecules & Compounds
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25. Pure substances
Compounds
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26. Mixtures
Combination of two or more pure substances. Substances are mixed together but have not reacted to form any new molecules.
Example- Sugar (a compound) dissolves in water (a compound) to form a mixture. The molecules of sugar and water do not change chemically. They just become mixed together.
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27. Properties of Matter
Physical properties – can be observed without changing the substance into a different substance.
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28. Chemical Properties
Characteristics of a substance that are observed when it reacts (changes) to produce one or more different substances.
Example- Water can be changed into hydrogen gas and oxygen gas using an electric current. When water molecules change chemically into hydrogen gas and oxygen gas, we say that a chemical change has occurred. Hydrogen gas and oxygen gas each have a different set of properties.
Substances change into different substances through chemical reactions.
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29. Chemical Reactions
Substances change into other substances in chemical reactions.
The atoms in the original substance are rearranged. The bonds in the original substance may be broken and new bonds may be formed between different atoms. This produces one or more new substances that may be either pure elements or compounds.
The products of a chemical reaction always have difference chemical and physical properties than the original substance(s).
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32. Chemical Equations
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33. Balancing Equations
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