Elements and Compounds
What is the difference between an element and a compound?
An element is a pure substance made of only one kind of atom.
A compound is a substance made of two or more different elements that are chemically bonded.
What is a molecule?
A molecule is a group of two or more atoms chemically bonded together.
What is quantum physics the study of?
The behavior of matter and energy at very small scales.
What is the symbol for oxygen?
O.
What does the Law of Conservation of Mass state?
Mass cannot be created or destroyed in a chemical reaction.
Why can’t elements be broken down into simpler substances by chemical means?
Because elements are already in their simplest form — they are made of only one type of atom.
Which is smaller, an atom or a molecule?
An atom is smaller.
What is the smallest unit of light called?
A photon.
How many elements are in the periodic table?
118.
Who is credited with formulating the Law of Conservation of Mass?
Antoine Lavoisier.
How can you tell if a substance is a compound just by looking at its chemical formula?
If the formula contains two or more different element symbols then it’s a compound.
What is the difference between a molecule and a compound?
A molecule is any group of two or more atoms bonded together, while a compound is a molecule made of two or more different elements.
Which famous scientist developed the quantum theory of energy levels in atoms?
Niels Bohr.
Which element has the atomic number 1?
Hydrogen (H).
In a chemical reaction, if you start with 10 grams of reactants, how many grams of products should you have?
10 grams.
How are compounds formed from elements?
Compounds form when atoms of different elements join together through chemical bonds (like ionic or covalent bonds).
How are molecules held together?
By chemical bonds.
What is quantum superposition?
It’s when a particle can exist in multiple states at once until it is measured or observed.
What are the horizontal rows in the periodic table called?
Periods.
Does the Law of Conservation of Mass apply to physical changes, chemical changes, or both?
Both, because mass is conserved in any type of change.
What is the smallest particle of an element, and what is the smallest particle of a compound?
Smallest particle of an element: Atom
Smallest particle of a compound: Molecule
Can molecules be made of the same type of atom or different types of atoms?
Yes, they can be made of the same type or different types.
What happens to a quantum system when it is observed or measured?
The system’s wavefunction collapses.
Why do elements in the same column of the periodic table act alike?
Because they have the same number of outer electrons.
Why does the mass of substances not change during a chemical reaction?
Because atoms are rearranged during the reaction, but no atoms are lost or gained.