Key Terms
What does absorb mean ?
absorb – to take in or soak up a substance, such as when a sponge soaks up water or a material takes in heat or light.
What is the term for a column on the Periodic Table that contains elements with similar chemical properties ?
A group
What is the term for a substance that starts or takes part in a chemical reaction ?
reactants
What is the term for a combination of two or more substances that are not chemically bonded and can be separated by physical means ?
A mixture
How many different elements make up methane [CH4] ?
2
What is the force that holds atoms together in a molecule or compound ?
a bond
What is an element?
a pure substance made of only one type of atom that cannot be broken down by chemical means.
What is the definition of a chemical reaction ?
A process in which substances interact to form new substances with different properties.
What is the term for a substance that cannot dissolve in a particular liquid ?
insoluble
How many atoms are there in methane [CH4] ?
5
What is a substance made of two or more elements chemically combined in a fixed ratio ?
a compound
What is the atomic number ?
the number of protons in the nucleus of an atom, which determines the element’s identity.
Describe 3 signs of a chemical reaction.
color change
temperature change
precipitate
bubbles
What is an alloy?
A mixture of two or more metals, or a metal and another element, made to improve strength or other properties
Which is an alloy ? 1) copper 2) sodium chloride 3) steel 4) methane
What is a prediction ?
a statement about what will happen based on observations or prior knowledge
How are elements arranged on The Periodic Table ?
by their atomic number and chemical properties
What is the name fo a solid that forms and separates from a liquid during a chemical reaction ?
A precipitate
What is the term for a substance formed as a result of a chemical reaction ?
A product
How are chemical changes and physical changes different ?
A chemical change creates a new substance with different properties and is generally irreversible, while a physical change alters a substance's form but not its chemical identity, and is typically reversible.
What word do we use to describe a substance that can dissolve in a liquid to form a solution ?
soluble
Which element in a group has the largest atomic number ?
The one at the bottom of the group [column]
What can form when 2 soluble compounds in a solution react?
A precipitate
Which one of these is a compound ? 1) air 2) nitrogen 3) carbon dioxide 4) air
carbon dioxide
Brass is an alloy that contains copper and zinc. Why is brass harder than copper ?
The atoms are different sizes, the layers of the atoms in brass are irregular, it is more difficult for atoms to move / slide