STAAR Need to Know1 STAAR Reporting Category 1 Matter & Energy Middle School Science Science STAAR Need to Know

STAAR Need to Know2 Atomic Theory Atoms are building blocks of elements Atoms are building blocks of elements Atoms in each unique element are the same. (Ex: Every oxygen element has the same # of protons) 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) 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- H 2 O ) Two or more different atoms bond in simple ratios to form compounds (Ex: Hydrogen & oxygen can chemically combine to form water- H 2 O )

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5 Atoms and Elements

STAAR Need to Know6 Atomic Particle Charges Protons Positive + Neutrons Neutral = Electrons Negative -

STAAR Need to Know7 Location of Subatomic Particles cm cm electrons electrons protons protons neutrons neutrons cm cm nucleus

STAAR Need to Know8 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???

STAAR Need to Know9 Periodic Squares 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!!!! 11Na22.99

STAAR Need to Know10 Atomic Mass on the Periodic Table 11Na22.99 Atomic Number or Protons Symbol Atomic Mass or Protons + neutrons

STAAR Need to Know11 Atomic number Atomic number = Atomic number = # of Protons # of Protons

STAAR Need to Know12 Mass Number The number of protons and neutrons in an atom

STAAR Need to Know13 Number of Electrons A balanced atom is neutral A balanced atom is neutral The net overall charge is zero The net overall charge is zero Number of protons = Number of electrons Number of protons = Number of electrons Atomic number = Number of electrons Atomic number = Number of electrons

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STAAR Need to Know17 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.

STAAR Need to Know18 Metals & Nonmetals

STAAR Need to Know19 ElementProtonsNeutronsElectrons 2 elements with similar properties Chlorine F and Br Iron-56 Magnesium-24 Lead-208 Nitrogen Ru and Os 12 Ca and Sr Sn and Ge P and As

STAAR Need to Know20 Molecules & Compounds

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STAAR Need to Know22 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.

STAAR Need to Know23 Properties of matter Physical properties – can be observed without changing the substance into a different substance.

STAAR Need to Know24 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.

STAAR Need to Know25 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).

Evidence of a Chemical Reaction a change in odor, a change in odor, a change in color, a change in color, a solid precipitate is formed, a solid precipitate is formed, a gas is formed, a gas is formed, there is either absorption or release of heat there is either absorption or release of heat STAAR Need to Know26

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STAAR Need to Know29 Chemical Equations

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