Elements
This element, symbol O, is essential for respiration in humans.
Oxygen
This state of matter has a definite shape and a definite volume. What is it?
solid
This is the basic unit of life found in all living organisms. What is it?
the cell
This is the smallest unit of matter that still has the properties of an element. What is it?
An atom
The unit used to measure force is named after this famous scientist. What is it?
the Newton
This element with the symbol Na is found in table salt.
sodium
This state of matter takes the shape of its container but keeps a constant volume. What is it?
liquid
This organelle is known as the “powerhouse of the cell” because it produces energy. What is it?
The mitochondria
A combination of two or more elements chemically bonded together is called what?
A compound
This force pulls objects toward the center of the Earth. What is it?
Gravity
This gas, symbol He, is the second most abundant element in the universe and is used in balloons because it is less dense than air.
Helium
In this state of matter, particles move freely and spread out to fill any available space. What is it?
gas
Plants make their own food using sunlight in a process called what?
Photosynthesis
The pH scale measures how acidic or basic a substance is. A pH of 7 is considered what?
Neutral
The amount of energy an object has due to its motion is called what?
Kinetic energy
This element, number 26 on the periodic table, is the most common metal used in construction and makes up Earth’s core.
Iron
This high‑energy state of matter is made of ionized gas and is found in stars and lightning. What is it?
Plasma
This molecule carries genetic information and determines inherited traits. What is it?
DNA
When a solid turns into a liquid, the process is called what?
Melting
Isaac Newton
This element is the only metal that is liquid at room temperature and has the symbol Hg. It was historically used in thermometers.
mercury
The process in which a solid changes directly into a gas without becoming a liquid—like dry ice turning into carbon dioxide gas—is called what?
Sublimation
This system in the human body transports nutrients, oxygen, and hormones throughout the body and removes waste products. What is it?
The circulatory system
The number of protons in an atom determines the element’s identity and is called what?
Atomic number
This law states that for every action, there is an equal and opposite reaction. What is it?
Newton’s Third Law of Motion