Structure and Properties of Matter
Define an element and give one example.
Varies
State the law of conservation of mass in a chemical reaction in one sentence.
In a chemical reaction, matter is never created or destroyed; it only changes form, so the total amount of stuff you start with is the same as the total amount you end with.
Define kinetic energy and give one everyday example.
Kinetic energy is the energy an object possesses due to its motion. Any object that is moving—whether walking, falling, or flying—has kinetic energy, which depends on both its mass and its speed.
State Newton’s First Law (law of inertia) in one sentence.
An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced external force.
State one major difference between light waves and sound waves regarding medium requirements.
Light waves do not require a medium to travel (they can travel through a vacuum), whereas sound waves require a material medium (such as air, water, or solids).
Explain the difference between a homogeneous mixture and a heterogeneous mixture. Give one example of each.
homogeneous-varies
hetergeneous-varies
variety of examples
In an experiment, mass of reactants is 24.5 g. What should the mass of products be if mass is conserved? Explain
Imagine you have a big box of Lego bricks (the reactants). You weigh the box, and it weighs 24.5 grams.
Write the formula that shows how kinetic energy depends on mass and speed (name variables).
KE=1/2 mv2
If two students push identical carts with the same force, but one cart has twice the mass, which cart accelerates more? Explain using Newton’s Second
The lighter cart accelerates more. Newton’s second law of motion states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass, expressed by the formula
This is the physical length of one complete cycle of the wave (e.g., distance from crest to crest).
wavelength
Describe what happens to particle motion and spacing when a solid melts to become a liquid.
the particles move faster and spread out
Identify whether dissolving salt in water is a physical or chemical change and justify your choice with evidence.
Dissolving salt in water is generally classified as a physical change. While the process breaks ionic bonds to dissociate sodium chloride into individual sodium and chloride ions, it does not create a new chemical substance.
Explain how potential energy changes when an object is lifted higher above the ground.
When an object is lifted higher above the ground, its gravitational potential energy increases with height
Define balanced and unbalanced forces and give one classroom example of each.
Balanced forces occur when two or more forces acting on an object are equal in magnitude but opposite in direction, resulting in a net force of zero and no change in the object's motion (stays at rest or moves at a constant velocity).
Unbalanced forces occur when the forces acting on an object are unequal, resulting in a non-zero net force that accelerates the object (speeds it up, slows it down, or changes its direction).
This is the number of cycles that pass a given point in a set amount of time, usually one second (measured in Hertz, Hz).
frequency
List two chemical properties and two physical properties of matter. For each, give a specific example.
Chemical -flammability, toxicity, solubility, heat from combustion, radioactivity, types of chemical bonds formed, coordination number, oxidation, and acidity or basicity.
physical-color, opacity, size, volume, length
Given a balanced chemical equation
2H2+O2→2H2O
explain how the law of conservation of matter is shown using numbers of atoms.
the Law of Conservation of Matter is shown by the fact that the total number of atoms of each element on the reactant side is exactly equal to the total number of atoms of each element on the product side.
A 2-kg object moves at 3 m/s. Use the kinetic energy relationship to explain how changing speed affects kinetic energy (qualitative description — how a doubling of speed affects KE).
Doubling the speed results in the kinetic energy becoming four times its original value.
A 5-kg object experiences a net force of 10 N. Calculate its acceleration and state which law you used. (Show formula name.)
The acceleration of the object is 2, calculated using Newton's Second Law of Motion.
Describe what happens to light when it passes from air into water (name two phenomena)
refraction, speed change
Using the periodic table patterns, explain why elements in the same group have similar chemical behaviors.
similar chemical behaviors because they have the same number of valence electrons—electrons in their outermost shell
Design (briefly) an investigation to show conservation of mass during a chemical reaction that produces a gas. Include how you would collect data to demonstrate mass conservation.
Investigation: The Balloon Bottle Bash
Plan a simple graph to show the relationship between kinetic energy and speed. Describe which variables go on each axis and the expected shape of the graph.
KE vertical axis
velocity (speed) horizontal axis
Describe an experiment with a ramp and carts to investigate how mass affects acceleration.
Varies
measures the "height" or "strength" of the wave.
amplitude