Periodic Table
What is the name of the vertical columns on the periodic table?
Groups
What is a sign that a chemical reaction has taken place?
Colour change/gas produced/temperature change/precipitate formed
Which type of reaction releases heat?
Exothermic
What does a chemical reaction show?
Reactants and products in a chemical reaction.
What does the law of conservation of mass state?
Mass is neither created nor destroyed in a chemical reaction.
Which elements has the atomic number of 8?
Oxygen
Is burning wood a physical or chemical change?
Chemical
Which type of reaction absorbs heat?
Endothermic
In the word equation: hydrogen + oxygen -> water, what are "hydrogen" and "oxygen" called?
Reactants
In a closed conatiner, if you mix two chemicals and the mass stays the same before and after the reaction, what does this show?
Law of Conservation of Mass.
What do elements in the same group have in common?
The same number of valence electrons/properties.
What is the difference between a physical and a chemical change?
Is photosynthesis an endothermic or exothermic reaction?
Endothermic
Why must chemical equations be balanced?
To obey the law of conservation of mass.
In a closed system (lid), should the mass change after a chemical reaction?
No, it stays the same.
Why are noble gases unreactive?
They have a full outer electron shells.
What do we call it when two substances are mixed and bubbles form, but no heat is added?
A chemical reaction.
Give an example of an exothermic reaction.
Combustion/Heat Pack
What are the small numbers after symbols in a formula called?
Subscripts
Why might the mass seem to decrease in an open system (no lid) reaction?
Because gas might escape.
Which side of the periodic table are the metals located on?
Left
What is the name of the reaction where a substance combines with oxygen and produces heat?
Combustion
Why does temperature decrease during an endothermic reaction?
2 H2 + O2 -> 2 H2O
Yes