chemistry review

Which of the following is described as the basic unit of matter?

• Element
• Atom
• Molecule
• Compound

In the atom diagram shown, E is pointing to

• An electron
• a proton
• a neutron
• the nucleus

In the atom diagram shown, A is pointing to the darker particles, these are known as

• electrons

• protons

• neutrons

• the nucleus

B and C are found in the ______ of an atom.

• electron cloud
• Space
• Nucleus
• Outside

In this chemical equation, the elements in red are the_______.

• Products

• Reactants

• Subscripts

• Coefficients

What is the atomic mass of this atom?

• 1

• 3

• 4

• 7

What is the atomic number of this atom?

• 4
• 5
• 9
• none of the above

What is a valence electron?

• an electron that is found in the outermost orbital of an atom. 
• an electron found in the innermost orbital of an atom.
• an electron found in the middle orbital.

An ionic bond forms when

• valence electrons are shared back and forth (move between) two atoms.

• a sea of mobile electrons surround the cations and they then become negativly charged

• valence electrons are transferred from one atom to another, forming charged ions that are then pulled together by attraction between opposite charges

• none of the above

Covalent bonds form when

• the electronegativity difference between two atoms is very large.

• electrons are completely transferred between two atoms.

• pairs of electrons are shared between two atoms.

• ions are held together by opposite charges.