Combining Atoms and Molecules

What is the picture displaying?

• An element

• An atom

• A compound

• A nucleus

Which of these is a compound?

• Iron

• Potassium

• Salt

• Calcium

When there is no subscript after an element's symbol, it means there are how many atoms of that element?

• none

• only 1

• exactly 2

• the atomic number

Which of the following is the best description of an element?

• A substance that cannot be broken down into simpler substances.

• A naturally occurring mineral made of more than one substance.

• A small particle made with a specific chemical composition.

• A collection of atoms that have different abilities when joined together.

How are elements and compounds different?

• A compound is represented by a chemical formula, and elements are represented by a chemical symbol.

• Compounds are represented by chemical symbols of one letter, and elements are represented by symbols of two letters.

• Elements are pure substances, and compounds are not.

• Elements are always larger units of matter, and compounds are smaller.

Hydrogen is considered an element, while hydrogen peroxide is considered a compound. This is because hydrogen peroxide is...

• is used for cleaning wounds.

• made of two different elements.

• is a liquid.

• useful to human beings.

Which of the following represents an element?

• H₂O

• HCl

• NaCl

• Au

• CaCO₃

Why do all bonds form?

• to fill the outermost energy level

• so an atom can be unstable

• so the number of protons and electrons can equal.

• so they can gain neutrons.

An atom with 1 valence electron 'needs' a full shell, so it can either gain 7 electrons or lose 1. Which is more likely to occur?

• nothing

• gain 7

• lose 1

• both

How do covalent bonds form?

• by sharing electrons between atoms

• by donating or receiving electrons