Reactions
An _____ reaction absorbs energy
endothermic
Hydrogen is the ______ element of the periodic table.
Accepted answers
- first
- lightest
Rows of elements are called
periods
The Law of Conservation of ___ tells us that matter cannot be created nor destroyed.
Mass
An ______ reaction releases energy
exothermic
______ makes up most of your body
Oxygen
Columns of elements are called _____.
Groups
The Law of Conservation of ___ tells us that energy cannot be created nor destroyed.
energy
A chemical reaction must always be ______.
Balanced
Cerium, Lutecium, and Neodymium are _______.
Lanthinides
Dmitri Mendeleev made the ______.
Periodic Table
Niels Bohr made a model of the _____.
Atom
Reactants react to make the ______.
product
Uranium is a _______ on the periodic table.
Actinide
______ are located at the center of the periodic table.
Transition Metals
Lawrencium, element 103 is named after _____.
Ernest Lawrence
______ are used to balance chemical equations
coefficients
Chlorine, Florine, and Bromine are in the same _____.
Group
_______ and Actinides are at the bottom of the periodic table.
Lanthanides
Unstable atoms usually have a _______, the duration being short or long.
half-life