Chemistry: Atoms and Periodic Table

What is the periodic table?

An ordering of the elements in columns and rows reflecting differences in atomic structure and the properties that result.

What do the two numbers on a periodic table entry mean?

The top number is the atomic number (number of protons); the bottom is the atomic mass.

What are the rows of the periodic table called?

Periods.

What are the columns of the periodic table called?

Groups.

Name four properties the periodic table reflects.

Number of protons, atomic size, ionization energy and electronegativity.

What is matter made of?

Atoms — whether the matter is solid, liquid, gas or plasma.

What is an atom made of?

Protons, neutrons and electrons.

What forms the atomic nucleus?

Positively charged protons joined with neutral neutrons.

What determines the type of atom?

The number of protons in its nucleus.

How many protons does oxygen have?

Eight — its atomic number is 8.

How many protons does carbon have?

Six — its atomic number is 6.

Where are electrons found in an atom?

In electron clouds around the nucleus, electrically attracted to the protons.

How does the number of electrons compare to protons in an atom?

They correspond — the number of protons matches the number of electrons.

What does the number of electrons determine?

The atom's ability to bond and the types of bonds it can form.

What is an atomic number?

The number of protons in an atom's nucleus.