PERIODIC TABLE
WHAT DO WE CALL THE HORIZONAL ROWS ON THE PERIODIC TABLE
PERIODS
WHAT IS A CHEMICAL CHANGE?
A CHANGE IN MATTER WHERE A NEW SUBSTANCE IS FORMED.
What is the Law of Conservation of Mass?
This law states that matter is not created or destroyed during a chemical reaction.
What is a physical change?
This type of change does not create a new substance and can often be reversed.
What is an atom?
the smallest unit of matter that makes up all elements.
WHAT DO WE CALL THE VERTICAL ROWS ON THE TABLE AND HOW MANY OF THEM ARE THERE
GROUPS/18
EXPLAIN HOW BAKING A CAKE IS A CHEMICAL CHANGE. GIVE TWO PIECES OF EVIDENCE TO SUPPORT THIS.
1. COLOR CHANGE
2. NEW SUBSTANCE FORMS WITH A NEW TEXTURE, TASTE AND PROPERTIES.
When 10 grams of a substance reacts and forms 10 grams of products, what law is being demonstrated?
Part B: What does this tell us about matter?
What is the Law of Conservation of Mass; matter is not created or destroyed only changed.
Cutting paper into smaller pieces and melting ice are examples of what type of change?
What happens to a substance during this type of change?
Answer: A physical change
Answer: The substance stays the same, only its size, shape, or state changes (no new substance is formed).
This part of the atom has a positive charge and is found in the nucleus.
Part B: What is the charge of an electron?
What is a proton; negative
NAME THE ELEMENT FROM THE TABLE THAT HAS AN ATOMIC NUMBER OF 11 AND NAME THE GROUP AND PERIOD THAT IT IS IN.
SODIUM, GROUP 1, PERIOD 3
A STUDENT CLAIMS THAT MELTING CHOCOLATE AND BAKING A CAKE ARE CHEMICAL CHANGES.
1. IS THE STUDENT'S CLAIM CORRECT?
2. COMPARE WHAT IS HAPPENING TO THE PARTICLES IN EACH
3. PROVIDE TWO PIECES OF EVIDENCE THAT SUPPORT YOUR CONCLUSION
1. THE CLAIM IS INCORRECT
2. MELTING CHOCOLATE-THE PARTICLES JUST SPREAD OUT AND STAY THE SAME. CAKE-PARTICLES REARRANGE TO FORM NEW SUBSTANCE
3. MELTING CHOCOLATE IS REVERSABLE
CAKE CAN'T BE REVERSED IT MADE A NEW SUBSTANCE. COLOR CHANGE, GAS PRODUCTION, SMELL
A student mixes vinegar and baking soda in an open cup and notices the mass seems to decrease.
Part A: Did mass actually disappear?
Part B: What gas is produced during this reaction?
Part C: Why does the mass seem to decrease?
Part A: No
Part B: Carbon dioxide (CO₂)
Part C: The gas escaped into the air, so it was not measured on the scale
A student crushes a soda can and then melts an ice cube.
Part A: Are both of these physical changes?
Part B: Give one piece of evidence for each example that supports your answer.
Part C: What is NOT formed during these changes?
Part A: Yes
Part B: Crushing = shape change; Melting = state change
Part C: No new substance is formed
Atoms are made of three main subatomic particles.
Part A: Name all three particles.
Part B: Which particles are found in the nucleus?
Part C: The atomic number of an element is 11. What does this tell you?
Part D: If the atomic mass is 23, how many neutrons does this atom have?
Part A: Protons, neutrons, electrons
Part B: Protons and neutrons
Part C: It has 11 protons (and 11 electrons if neutral)
Part D: 23 − 11 = 12 neutrons
WHAT IS THE ELEMENT THAT HAS AN CHEMICAL SYMBOL OF W. THEN STATE HOW YOU WILL CALCULATE HOW MANY NEUTRONS ARE IN THE ATOM. THEN TELL US THE NUMBER OF NEUTRONS.
TUNGSTEN.
TO FIND NEUTRONS TAKE THE ATOMIC MASS OF 184 AND SUBTRACT FROM THE 74. THE NEUTRON COUNT IS 110
A STUDENT BURNS A PIECE OF PAPER AND OBSERVES SMOKE, HEAT AND ASHES FORMING.
1. WHAT TYPE OF CHANGE IS OCCURING?
2. IDENTIFY TWO PIECES OF EVIDENCE THAT A CHEMICAL CHANGE HAS TAKEN PLACE.
3. WHAT NEW SUBSTANCES ARE FORMED DURING THIS PROCESS?
4. EXPLAIN WHY THIS CHANGE CANNOT BE REVERSED.
1. CHEMICAL CHANGE
2. EVIDENCE INCLUDES HEAT/LIGHT PRODUCED, GAS (SMOKE) NEW SUBSTANCE FORMED.
3. ASH, CARBON DIOXIDE GAS, WATER VAPOR
4. IT CAN NOT BE REVERSED BECAUSE NEW SUBSTANCES ARE FORMED AND THE ORGINAL PAPER CANNOT BE RECREATED.
In a closed system, 25 g of reactants produce 18 g of one product.
Part A: How many grams must the other product have?
Part B: Why must this be true?
7 grams; because mass must be conserved (total stays 25 g).
A student dissolves sugar in water and compares it to burning sugar.
Part A: Which is a physical change and which is a chemical change?
Part B: What is happening to the particles in the physical change?
Part C: Give two reasons why dissolving sugar is a physical change.
Part D: How could you reverse the physical change?
Part A: Dissolving = physical; Burning = chemical
Part B: Particles spread out but remain the same substance
Part C: No new substance, can be reversed
Part D: Evaporate the water to get the sugar back
An atom has an atomic number of 17 and an atomic mass of 35.
Part A: How many protons does it have?
Part B: How many electrons does it have if it is neutral?
Part C: How many neutrons does it have?
Part D: What element is this?
Part A: 17 protons
Part B: 17 electrons
Part C: 35 − 17 = 18 neutrons
Part D: Chlorine
STATE HOW THE PERIODS ARE ORGANIZED (THREE THINGS) STATE HOW GROUPS ARE ORGANIZED (TWO WAYS)
PERIODS-INCREASING ATOMIC NUMBER AND MASS
-EACH PERIOD HAS THAT NUMBER OF ELECTRON SHELLS. (PERIOD 1 -ONE SHELL, PERIOD 2 TWO SHELLS ETC.
GROUPS-ORGANIZED BY THE NUMBER OF VALENCE ELECTRONS AND BY IT'S PROPERTIES
A STUDENT OBSERVES TWO SITUATIONS:
-ICE MELTING INTO WATER
-A BIKE RUSTING OUTSIDE
1. IDENTIFY WHICH SITUATION IS A CHEMICAL CHANGE AND WHICH IS A PHYSICAL CHANGE.
2. DESCRIBE WHAT IS HAPPENING TO THE ATOMS/PARTICLES IN EACH SITUATION.
3. GIVE TWO PIECES OF EVIDENCE THAT PROVE THE CHEMICAL CHANGE HAS OCCURED.
4. EXPLAIN WHY ONE OF THESE CHANGES IS EASILY REVERSIBLE AND THE OTHER IS NOT.
Part A:
Ice melting = Physical change
Rust forming = Chemical change
Part B:
Melting: particles spread out but stay the same substance (H₂O)
Rusting: atoms rearrange to form a new substance (iron oxide)
Part C:
Evidence: new substance forms, color change (reddish rust), cannot easily reverse
Part D:
Melting is reversible (can freeze again)
Rusting is not easily reversible because a new substance forms with different properties
A student conducts an experiment burning steel wool and observes that the mass increases.
Part A: Does this violate the Law of Conservation of Mass?
Part B: Explain what is happening at the atomic level.
Part C: Identify what substance is being added to the steel wool.
Part D: Explain how this experiment actually supports the law.
Part A: No
Part B: Atoms are rearranging and combining with oxygen
Part C: Oxygen from the air
Part D: Mass increases because oxygen is added, showing total mass is still conserved when all matter is accounted for
A student claims that melting, freezing, and boiling water are all different types of changes.
Part A: Are these physical or chemical changes?
Part B: Explain what is happening to the particles during these changes.
Part C: Why are these changes considered reversible?
Part D: Explain why no new substance is formed even though the appearance changes.
Part A: Physical changes
Part B: Particles move faster/slower and spread out or come closer together
Part C: They can change back by heating or cooling
Part D: The substance remains H₂O the entire time
Two atoms are shown below:
Atom A: Atomic number = 20, Atomic mass = 40
Atom B: Atomic number = 20, Atomic mass = 42
Part A: What element are both atoms?
Part B: How many protons does each atom have?
Part C: How many neutrons are in Atom A and Atom B?
Part D: What are these two atoms called?
Part E: Explain how the difference in neutrons affects the atoms.
Part A: Calcium
Part B: 20 protons each
Part C:
Atom A: 40 − 20 = 20 neutrons
Atom B: 42 − 20 = 22 neutrons
Part D: Isotopes
Part E: They have the same element but different masses; extra neutrons can affect stability (some isotopes may be unstable)