Chapter 2

Consits of one type of atom only

Made up of two or more different elements which are chemically bonded together -> properties of compound differ from properties of original elements + difficult to seperate

Made up of two or more elements or compunds that aren’t chemically bonded together -> properties of mixture: a mixture of the properties of seperate parts + easily seperated with pysical methods

Central nucleus containing protons and neutrons surrounded by electrons in shells

No overall charge as number of protons is equal to number of electrons -> if some electrons are added or removed the atom becomes charged and is now an ion

1

1

Approx 0 -> 0.0005

+1

0

-1

Number of protons in nucleus of atom -> in neutral atom this tells us the element (Smaller number)

Number of protons and neutrons in nucleus of atom (Bigger number)

Different atoms of the same element that have the same number of protons but different number of neutrons - Isotopes have the same chemical properties, as chemical properties depend on the number of electrons and isotopes have the same number of electrons/electronic configuration

Average mass of all isotopes of the element

• Electrons always occupy shells (energy levels) • Lowest shells always filled first -> shells closest to nucleus • Certain capacity of electrons in each shell

2 electrons

8

Control reactivity as they from bonds with other atoms to gain or loose enough electrons to achieve a full outer shell and become stable + unreative

Charged particles

Negative ions -> form when atoms gain electroms

Positive ions-> form when atoms loose electrons

Between metals and non-metals -> metal atom looses electrons to form a cation and a nonmetal gains these electrons to form an anion - These oppositely charged ions are strongly attracted to each other by electrostatic attractions -> ionic bonding

Always have gaint ionic structure -> regular arrangement of alternating positive and negative ions - High melting/boiling points (low volatility) -> strong attractive forces between closely packed ions in giant ionic lattice (takes a lot of energy no break bonds) - When solid -> can’t conduct electricty but do conduct when aqueous or molten -> ions are mobile and carry electric charge