Objective 3 Review The student will demonstrate an understanding of the structures and properties of matter.

Parts of an Atom ELECTRON - PROTON + NUCLEUS ELECTRON CLOUD NEUTRON no charge

An atom has a neutral charge An atom has a neutral charge. Which of the following must be true about the atom? It must have the same number of electrons and neutrons. It must have more protons than electrons. It must have the same number of electrons and protons. It must have more neutrons than protons. TMSDS 8.8A

Each atom has a different number of neutrons. Look at the two atomic models below. How can you tell that the two atoms represent different elements? Each atom has a different number of neutrons. Each atom has the same number of protons and neutrons. Each atom has the same number of protons. Each atom has a different number of protons. TMSDS 8.8A

Ions and Isotopes ISOTOPES The atoms have thesame number of protons, but have different numbers of neutrons. They have different masses. Isotopes can be radioactive. IONS The atoms have either lost or gained an electron in their outer shell and have an overall positive or negative charge. Ions are likely to undergo chemical reactions.

The sodium atom has an unequal number of protons and electrons The sodium atom has an unequal number of protons and electrons. Why is it considered to be an ion with a +1 electrical charge? The sodium atom has an extra electron, giving it a positive charge. The sodium atom has an extra neutron, giving it a neutral charge. The sodium atom has given up an electron, giving it a positive charge. The sodium atom has given up a proton, giving it a positive charge. TMSDS 8.8B

Element Keys ATOMIC NUMBER = # of PROTONS ELEMENT SYMBOL The 1st letter is CAPS and if there is a 2nd letter it is lowercase. ELEMENT NAME ATOMIC MASS = # of NEUTRONS + # of PROTONS

Carbon dioxide is a gas that is found in the air you breathe out Carbon dioxide is a gas that is found in the air you breathe out. Carbon dioxide is made up of two different pure substances, carbon and oxygen. Which of the following would be classified as an element? air gas oxygen Carbon dioxide TMSDS 7.7C

REMEMBER – GROUPS of elements have SIMILAR PROPERTIES! Periodic Table GROUP/ FAMILY (column) http://www.elementsdatabase.com/Images/periodic_table.gif PERIOD (row)

Use your periodic table to answer the following question Use your periodic table to answer the following question. Which element on the periodic table has physical properties MOST similar to the physical properties of chlorine? Sodium Sulfur Fluorine Argon TMSDS 8.9B

An element in Group 2 on the periodic table MOST likely has which physical property? a dull rough surface in the solid phase a boiling point far below 0°C high malleability low conductivity TMSDS 8.9B

Organization CHEMICAL CHANGE PHYSICAL CHANGE

4H2O Counting Atoms 4 molecules of water NOTHING = the element symbol stand for 1 atom COEFFICIENT = the number of molecules; multiply by everything in the formula SUBSCRIPT = the number of atoms of that element

This is the chemical formula for a sample of matter: 3H2SO4 How many atoms of oxygen are found in this sample of matter? 3 4 7 12 TMSDS 8.9C

States of Matter Review

Physical vs Chemical Change Chemical changes involve: rusting / corrosion reacting / reaction / digesting burning / combustion bubbling / fizzing / giving off a gas ***Everything else is a physical change*** (dissolving, boiling, melting, freezing, tearing, changing shape)

Maurice bought a bag of onions to make a large pot of onion soup Maurice bought a bag of onions to make a large pot of onion soup. He cut the onions into small strips and then put them into a pot with butter to cook. Why was cooking the onion a chemical change, while cutting the onion was not? Cutting the onion caused the shape of the onion to change. Mixing the ingredients together created a chemical reaction. Cooking the onion did not cause a permanent change in its molecular structure. Cooking the onion caused a permanent change in its molecular structure. TMSDS 6.7

Bubbles form as the two liquids mix together. Mrs. Henderson conducts a class demonstration. She pours a test tube of a blue liquid into a beaker containing a clear liquid. Which of the following observations could be evidence that a chemical reaction does NOT take place? Bubbles form as the two liquids mix together. White powder settles on the bottom of the beaker. The temperature of the liquid increases. The temperature of the beaker remains the same after the liquids mix. TMSDS 8.9A

Chemical Reactions REACTANTS PRODUCTS You show a chemical reaction with a CHEMICAL FORMULAS and EQUATIONS. Carbon dioxide + water + sunlight = sugar + oxygen 6CO2 + 6H2O + light → C6H12O6 + 6O2 REACTANTS They “REACT” together. PRODUCTS They are “PRODUCED” by the reaction. The arrow means “equals”

A student researches the chemical reaction that forms a certain kind of plastic. Which format is BEST for summarizing information about the reaction? A chemical formula A chemical equation A data table A written paragraph TMSDS 8.9C

Endothermic/Exothermic Heat must be added to make the chemical reaction happen. It is written as a reactant. EXOTHERMIC Heat is produced during a chemical reaction. The temperature will go up. It is written as a product. Reactants + HEAT → Products Reactants → Products + HEAT

Water has a higher specific heat than land. The amount of energy it takes to raise the temperature of 1 gram of a substance 1 oC. It is a physical property and depends on how much of the substance you have. Water has a higher specific heat than land. The land heats up and cools off more quickly – lower specific heat. The water heats up and cools off more slowly – higher specific heat.

Law of Conservation of Mass During a chemical change (reaction), the total mass stays the same, even though it may change forms. Ex: If you start with 5 grams of Zn and 2 grams of Oxygen and it all completely reacts to form ZnO, there must be ___ grams of ZnO formed. The number of each type of atom on each side of the equation must always be equal. Ex: ___ H2 + ___ O2  ___ H2O 7 2 2