Changes in Matter
A change in which a substance's form or appearance changes, but its chemical identity stays the same.
Physical Change
Heat transfers from a hot pan to a metal spoon touching it.
Conduction
The scientific law stating matter cannot be created or destroyed during a physical or chemical change.
Law of Conservation of Mass
The number of protons in an atom that determines the element's identity.
Atomic Number
This is the smallest unit of an element that still has the properties of that element.
atom
A change that produces one or more new substances.
Chemical change
Warm water rises while cooler water sinks, creating a circulating current.
Convection
A sealed container holds 50 g of reactants. What is the mass of the products?
50g
The vertical columns containing elements with similar chemical properties.
Groups or families
This is a pure substance made of only one type of atom.
element
A student tears a piece of paper into smaller pieces. Identify the change.
Physical change
Energy from the Sun travels through space and warms Earth.
Radiation
Gas escapes into the air during a chemical reaction. Is this an open or closed system?
Open System
The horizontal rows of the periodic table.
Periods
Water (H₂O) contains two hydrogen atoms and one oxygen atom chemically combined. Water is an example of this type of substance.
Compound
A bicycle is left outside and begins to rust. Identify the change.
Chemical Change
In which direction does thermal energy naturally transfer?
Warmer to cooler
Substances with masses of 35 g and 45 g react completely in a closed system. What is the mass of the products?
80g
Elements near the staircase that have properties of metals and nonmetals.
Metalloids
A student examines two substances. Substance A contains only oxygen atoms, while Substance B contains carbon and oxygen atoms chemically combined. Which substance is a compound?
Substance B
Two clear liquids are mixed, forming a new solid that settles at the bottom. Identify the change.
Chemical Change
A metal bench feels colder than a wooden bench at the same temperature because it transfers heat away from your hand faster. What process explains this?
Conduction
A reaction produces 40 g of one product and 25 g of another. If one reactant had a mass of 50 g, what was the mass of the other reactant?
15g
Two elements have similar chemical properties but different atomic numbers. Are they more likely in the same group or period?
Same group
A scientist discovers a substance containing 3 different types of atoms chemically combined. The scientist claims it cannot be a compound because compounds contain only 2 types of atoms. Explain why the scientist is incorrect.
a compound can contain two or more different elements chemically combined