Forms of Energy
When a moving object collides and energy changes forms without being lost, this law explains that the total energy stays the same.
Law of Conservation of Energy
The number at the top of each element’s box tells you this about the atom.
Atomic number (number of protons)
Carbon dioxide (CO₂) cannot be separated by physical means because it is this type of substance.
Compound
Elements in the same group have the same number of these.
Valence electrons
A flashlight shines on a wall. The battery provides energy that is converted into light and heat. Name the two forms of energy in this scenario.
Chemical and light energy
These elements, found on the far right of the periodic table (except hydrogen), are very unreactive.
Noble gases
Sugar dissolves in water. Is this a physical or chemical change? Explain why.
Physical change, because the sugar can be recovered by evaporating the water and no new substance is formed.
This type of energy comes from sources that can be replaced naturally over a short period, like sunlight, wind, and water.
Renewable energy
A 2-kg skateboard rolls down a hill at a speed of 3 m/s. What is the skateboard's kinetic energy?
9 joules (J)
Elements that have properties of both metals and nonmetals are called this.
Metalloids
Nitrogen is an example of a what?
Element
A student rolls a 3-kg ball at 4 m/s across the floor. Calculate the kinetic energy of the ball.
24 joules (J)
Coal, oil, and natural gas are examples of this type of energy because they cannot be replaced quickly once used.
Nonrenewable energy
These metals on the periodic table are considered good conductors.
Transition metals
When a glow stick is snapped and begins to glow, this type of change has occurred because energy is released and new substances form.
Chemical change
A student heats water on a stove until it boils. Identify the type of energy transferred to the water and whether any chemical change occurs.
Kinetic energy and physical change
Water behind a dam flows downward and spins turbines to produce electricity. What forms of energy are being converted in this process?
Gravitational potential energy, kinetic energy, and electrical energy
These elements in Group 1 of the periodic table are very reactive because they have one electron in their outermost shell that they easily lose.
Alkali metals
A solid, liquid, and gas all have the same mass of water. How are the particles arranged differently in each state of matter?
In a solid, particles are tightly packed and vibrate in place; in a liquid, particles are close but can move past each other; in a gas, particles are far apart and move freely.
A truck carrying sand stops suddenly, and the sand spills out. Explain how energy is transferred in this situation.
Kinetic energy of the truck transferring to kinetic energy of the sand, some energy is also lost as sound and heat