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

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 ) TAKS Need to Know

solid liquid gas TAKS Need to Know http://www.harcourtschool.com/activity/states_of_matter/ gas TAKS Need to Know

TAKS Need to Know

Atoms and Elements TAKS Need to Know

Atomic Particle Charges Protons Positive + Neutrons Neutral = Electrons Negative - TAKS Need to Know

Location of Subatomic Particles 10-13 cm electrons protons neutrons 10-8 cm nucleus TAKS Need to Know

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??? TAKS Need to Know

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!!!! TAKS Need to Know

Atomic Mass on the Periodic Table Atomic Number or Protons 11 Na 22.99 Symbol Atomic Mass or Protons + neutrons TAKS Need to Know

Atomic Number Atomic number = # of Protons TAKS Need to Know

The number of protons and neutrons in an atom Mass Number TAKS Need to Know

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 TAKS Need to Know

TAKS Need to Know

TAKS Need to Know

TAKS Need to Know

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. TAKS Need to Know

Metals & Nonmetals TAKS Need to Know

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 TAKS Need to Know

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). TAKS Need to Know

TAKS Need to Know

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. TAKS Need to Know

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. TAKS Need to Know

Molecules & Compounds TAKS Need to Know

Pure substances Compounds TAKS Need to Know

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. TAKS Need to Know

Properties of Matter Physical properties – can be observed without changing the substance into a different substance. TAKS Need to Know

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. TAKS Need to Know

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). TAKS Need to Know

TAKS Need to Know

TAKS Need to Know

Chemical Equations TAKS Need to Know

Balancing Equations TAKS Need to Know