Elements & Compound
What is the difference between an element and a compound?
An element is made of only one type of atom.
A compound is made of two or more different elements chemically bonded together.
A metal spoon is placed into a cup of hot soup. After a few minutes, the handle of the spoon becomes hot.
Which type of heat transfer caused the handle to warm up?
Conduction.
What is the mathematical formula for speed?
Speed = Distance ÷ Time
Which group of planets has stronger gravity overall: the inner planets or the outer planets?
The outer planets
A distance–time graph shows a line that slopes upward, then becomes flat, and finally slopes downward.
Describe what is happening to the object’s motion during each part of the graph.
Moving away from the start
Stopped
Moving back toward the start
The chemical formula H₂O represents a molecule of water.
How many total atoms are in one molecule, and how many different elements are present?
Total atoms: 3
Number of elements: 2 (Hydrogen and Oxygen)
What are the 3 forms of heat transfer. Provide an example for one form.
Conduction, Convection, Radiation. Ex: Touch, Currents, Sun or waves.
A distance–time graph shows three different sections:
one section with a positive slope,
one section with a negative slope,
and one flat (horizontal) section.
Positive slope: the object is moving away from the starting point
Negative slope: the object is moving back toward the starting point
Flat slope: the object is not moving (at rest)
Liquid water, presence of an atmosphere, and distance from the sun.
Distance from the sun is most important.
Two students travel the same distance. One takes twice as long as the other.
Who has the greater speed, and how do you know?
The student who took less time has the greater speed because speed equals distance divided by time.
The chemical formula MgCl₂ is shown below.
How many total atoms are in one formula unit, and how many different elements are present?
Total atoms: 3
Mg: 1
Cl: 2
Number of elements: 2 (Magnesium and Chlorine)
When the temperature of a substance increases, what happens to the motion of its particles, and what does this tell you about its thermal energy?
The particles move faster, which means the substance has more thermal energy or kinetic energy.
A car travels 60 miles in 3 hours.
What is the car’s average speed?
20 miles per hour.
Describe three differences between the inner planets and the outer planets.
Composition: Inner planets are rocky, outer planets are gas/ice giants
Location: Inner planets are closer to the Sun, outer planets are farther from the Sun
Size: Inner planets are smaller, outer planets are much larger
Moons/Rings: Inner planets have few or no moons and no rings, outer planets have many moons and ring systems
Atmosphere: Inner planets have thin or no atmospheres, outer planets have thick atmospheres
A hot cup of cocoa cools down faster when left uncovered than when a lid is placed on top.
What is happening to the thermal energy, and why does the lid change the cooling rate?
Thermal energy is transferring from the cocoa to the surroundings
The chemical formula Al₂(SO₄)₃ represents a compound made of aluminum, sulfur, and oxygen.
How many total atoms are in one formula unit, and how many atoms of oxygen are present?
Total atoms: 17
Al: 2
S: 3
O: 12
Oxygen atoms: 12
A cup of hot water is left on a table in a cool room. After 30 minutes, the water’s temperature has decreased.
What happened to the thermal energy of the water, and how did it move?
The water lost thermal energy, and the thermal energy transferred from the hot water to the cooler surroundings through heat transfer until temperatures became more balanced.
A student walks 240 meters down a hallway in 80 seconds.
What is the student’s average speed, and what does this value represent about the student’s motion?
Average speed: 240m(÷)80 s=3 m/s
This means the student travels 3 meters every second on average.
An object is located in the Kuiper Belt and has very little gravity, giving it an irregular shape. It orbits the Sun and is made mostly of ice and rock.
What type of object is this?
Comet
A soccer ball is kicked across a field and eventually slows down and stops.
According to Newton’s First Law, why doesn’t the ball keep moving forever?
Unbalanced forces, such as friction and air resistance, act on the ball and cause it to slow down and stop.
A compound is written as 3Ca(NO₃)₂.
How many total atoms are present, and how many different elements does the compound contain?
Total atoms: 27
Ca: 3
N: 6
O: 18
Number of elements: 3 (Calcium, Nitrogen, Oxygen
A metal spoon and a wooden spoon have been sitting in the same room all day and are at the same temperature. When you touch them, the metal spoon feels colder than the wooden spoon.
The metal spoon feels colder because it transfers thermal energy away from your hand more quickly than the wooden spoon.
Metal is a better conductor of heat, so thermal energy moves faster from your hand into the spoon.
A skateboarder is riding at a constant speed on a smooth, flat sidewalk. Suddenly, the skateboard hits a small rock and stops, but the rider continues moving forward and falls off.
Using Newton’s First Law, explain why the rider continues moving forward when the skateboard stops.
According to Newton’s First Law, an object in motion will remain in motion unless acted on by an unbalanced force. The skateboard experiences an unbalanced force from the rock and stops, but the rider’s body continues moving forward due to inertia until another force (such as the ground) stops it.
An object located in the Kuiper Belt orbits the Sun and has enough gravity to pull itself into a nearly spherical shape, but it does not have enough gravitational influence to clear its orbital path of other objects.
How should this object be classified, and which characteristics support this classification?
The object is a dwarf planet because it orbits the Sun, is nearly spherical due to its gravity, is located in the Kuiper Belt, and has not cleared its orbit of other objects.
An object orbits the Sun, is found between Mars and Jupiter