Matter & Energy
What are the four states of matter?
Solid, liquid, gas, plasma
What is the charge of a proton?
Positive
What type of bond forms when electrons are transferred?
Ionic bond
What is the role of the strong nuclear force?
It holds the nucleus together
What is the formula for speed?
Speed = distance ÷ time
Which state of matter has the most kinetic energy?
Plasma
Where are electrons located in an atom?
In the electron cloud outside the nucleus
What do subscripts in a chemical formula show?
The number of atoms of each element
What is the difference between radioactive and stable atoms?
Radioactive atoms decay; stable atoms do not
What is the difference between speed and velocity?
Velocity includes direction; speed does not
What is melting?
The change from solid to liquid
What is the atomic number?
The number of protons in an atom
Why must chemical equations be balanced?
To follow the law of conservation of mass
Which type of radiation has no charge?
Gamma
What does negative acceleration mean?
Slowing down or acceleration in the opposite direction
What is the difference between temperature and thermal energy?
Temperature is the average kinetic energy of particles; thermal energy is the total energy of all particles in a substance
What is the difference between an isotope and an ion?
Isotopes have different numbers of neutrons; ions have gained or lost electrons
What is the difference between endothermic and exothermic reactions?
Endothermic absorbs energy; exothermic releases energy
What is the difference between fission and fusion?
Fission splits atoms; fusion combines atoms
What is the formula for force?
Force = mass × acceleration
Why does ice float in water?
Ice is less dense than liquid water due to its molecular structure
How are elements arranged on the periodic table?
By increasing atomic number, organized into groups (columns) and periods (rows)
What type of reaction is: A + B → AB?
Synthesis reaction
If 25% of a substance remains, how many half-lives have passed?
2 half-lives
A car slows from 80 m/s to 20 m/s in 2 s. What is the acceleration?
a = (20 − 80) ÷ 2 = −30 m/s²