Science Unit 2

What are the three main subatomic particles in an atom?

Protons, neutrons, and electrons.

Where are protons located in an atom?

In the nucleus.

What determines the element of an atom?

The number of protons.

What is the charge of neutrons?

They have no charge.

How do electrons behave in relation to the nucleus?

They move in shells at varying distances.

What is the atomic number?

The number of protons in an atom.

What does the mass number represent?

Total number of protons and neutrons.

How many electrons can the first shell hold?

2 electrons.

What are valence electrons?

Electrons in the outer shell that determine chemical reactivity.

What does the periodic table arrange elements by?

Atomic number and properties.

What do elements in the same group have in common?

Similar chemical properties and the same number of outer shell electrons.

How do properties of elements change down a group?

They change gradually.

What is a characteristic of alkali metals?

They are very reactive.

What happens to reactivity in Group 1 as you go down the group?

Reactivity increases.

What defines noble gases?

Their outer electron shell is full.

Why do atoms react to form compounds?

To achieve a stable electron arrangement.

What is a full outer shell?

Having 8 electrons in the outer shell.

How do metals typically achieve stability?

By losing electrons to form positive ions.

What is a covalent bond?

A bond formed by sharing electrons.

What are simple molecular structures made of?

Small molecules held by covalent bonds.

What is a property of giant structures?

They have very high melting and boiling points.

What characterizes giant ionic structures?

Positive and negative ions in a giant lattice.

What is a property of metallic structures?

They are good conductors of electricity.