Elements and compounds
How many elements are known to exist?
118
What name is given to the vertical columns of the periodic table?
groups
What is a force?
Push or pull
What are the units of mass and weight?
Mass: kilograms (kg)
Weight: newtons (N)
What is the basic rule for naming compounds made of a metal and a non-metal?
Name the metal first, then the non-metal plus -ide.
Define element.
A substance containing only one kind of atom
As you move from right to left across a period in the periodic table, how do the properties of the elements change?
they become more metallic
What single word describes the effect of a force on an object’s motion?
Acceleration
What is the basic formula shown in the weight triangle.
W = mg
Oxygen combines with magnesium to form a compound. What is the name of the compound?
Magnesium oxide
Define compound.
A substance that contains two or more elements chemically combined.
Which pair of elements are in the same group?
A) Na and K
B) O and N
C) Mg and Al
A
Which property of an object has the greatest effect on air resistance as it falls?
surface area
An object has a weight of 200 N on Earth. What is its mass? (Take g=10 N/kg)
20 kg
How many oxygen atoms are in 2H₂O₂?
Four
True or false: all molecules are compounds
False (oxygen is an element that exists as a molecule O2)
Which element is found in both period two and group 4?
carbon
Which of the following forces is the odd one out?
A) Gravity
B) Air resistance
C) Magnetism
B. Air resistance is a contact force
you could also say C is not typically involved when an object falls
According to Newton’s law of gravitation, how can the gravitational force between two objects be increased?
bring them closer together
Name the compound with the formula CaCO₃
Calcium carbonate
Which metallic element with the symbol Hg is a liquid at room temperature?
mercury
Name the Russian who created the modern periodic table
Mendeleev
When an object reaches terminal velocity, what is true about the weight and air resistance acting on it?
they are the same
An astronaut has a mass of 70 kg. What happens to his mass when he travels to the Moon?
What is the full chemical name for water?