Core Unit 4 Big Test Review

• Two molecules combine to form one molecule

• Two atoms combine to form a molecule

• Two atoms combine to form one atom

• Two elements combine to form two new elements

Two gases can combine to form a new compound that is a liquid. What is a simple way to express what is happening in this chemical reaction?

• Write a chemical formula

• Write a chemical equation

• describe the rearrangement of atoms

• describe the procedure for creating this change

What makes the atoms of two different elements different?

• The number of protons

• The number of electrons

• The number of neutrons

• The number of ions

• Two atoms of Hydrogen and one atom of Oxygen

• a Water molecule

• Four atoms of hydrogen

• Two atoms of oxygen

Which atomic particle makes bonds happen between two elements to make molecules?

• protons

• Neutrons

• energy levels

• electrons

Two or more elements combine to form a

• element

• mixture

• compound

• atom

According to the modern model of atoms, an atom

• cannot be broken down into smaller pieces

• consists of a positively charged sphere in which negatively charged electrons are embedded like chocolate chips

• consists of a nucleus of negative charges surrounded by electrons that move around the nucleus

• consists of a nucleus containing protons and neutrons, with electrons moving in "clouds" around the nucleus

There is an element that makes up 78% of the Earth's atmosphere and it interacts with other elements to provide many of the nutrients needed in an ecosystem. What's the name of that element?

• Chlorine

• Nitrogen

• Oxygen

• Carbon

If you have a sample of an substance, what trait would the substance have to have in order for us to know it is an element and not a compound?

• The substance would be made of one type of atom

• The substance would be a liquid at room temperature

• The substance would contain different types of tiny particles

• The substance could only be seen under a microscope

Choose all of the compounds

• Sodium Chloride NaCl