Atoms & Elements
What is the smallest unit of matter that retains the properties of an element?
Atom
What type of reaction occurs when ice melts into water?
Physical reaction.
What is a molecule?
A group of two or more atoms bonded together.
Which subatomic particle has a positive charge?
Proton.
Solid, Liquid, Gas
What do we call a substance that is made entirely of one type of atom?
Element
What do we call a change where new substances with different properties are formed?
Chemical reaction
What do you call a substance made of two or more different elements chemically combined?
Compound
What is the charge of an electron?
Negative charge.
In which state of matter do particles move freely and spread out to fill their container?
Gas.
The atomic number of an element is based on the number of which particle in the atom?
Protons
What is a reactant in a chemical reaction?
The new substance formed after the reaction
True or False: All compounds are molecules, but not all molecules are compounds.
True
Which subatomic particle is found in the nucleus but has no charge?
Neutron.
What state of matter has a definite volume but takes the shape of its container?
Liquid.
How many elements are found in water (H₂O)?
Two elements (hydrogen and oxygen)
Which type of reaction can be easily reversed: chemical or physical?
Physical reaction
What is law of conservation of mass?
mass is neither created nor destroyed in chemical reactions
What two particles make up the nucleus of an atom?
Protons and neutrons.
What happens to mass during a chemical reaction in a closed system?
Stays the same
What is the term for the average mass of an atom of an element, taking into account all its isotopes?
Atomic weight (atomic mass)
What type of reaction occurs when baking soda reacts with vinegar, producing bubbles of carbon dioxide?
Chemical reaction.
How many oxygen atoms are there in one molecule of carbon dioxide (CO₂)?
Two oxygen atoms.
If an atom has 6 protons, 6 neutrons, and 6 electrons, what is its atomic number?
6 (the number of protons equals the atomic number).
What state of matter has a definite shape and volume?
Solid