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.
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
In which state of matter do particles move freely and spread out to fill their container?
Gas.
A reactions that releases energy (raises the temperature around it)
Endothermic or exothermic
exothermic
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
Oxygen, O2 is a compound
False
What state of matter has a definite volume but takes the shape of its container?
Liquid.
Reactions that absorb energy (feel cold)
endothermic or exothermic
endothermic
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
hydrogen peroxide: element or compound?
compound
What happens to mass during a chemical reaction in a closed system?
Stays the same
Name 2 signs of a chemical reactions
color change
energy change
odor change
precipitate formation (solid)
gas formation (bubbles)
What is the term for the mass on the periodic table ( 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.
What state of matter has a definite shape and volume?
Solid
If I mix baking soda and vinegar, are the bubbles of carbon dioxide that form a reactant or product?
product