Chem Comp Review_SC

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

Which of the following is found in the nucleus of an atom?

• electrons
• neutrons
• The center of an atom, composed of protons and neutrons
• molecules

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.

Is this image an example of covalent bonding?

• Yes
• No

What is made up two or more elements that are chemically combined?

• Atom

• Element

• Compound

• Mixture