Nature of Matter

Matter

• Anything that takes up space• Has mass• You are made up of matter…and so is

everything around you

Looking more closely at matter…

• Atoms: basic building blocks of matter

• Atoms are made up of Subatomic particles:

PROTONSNEUTRONSELECTRONS

Subatomic particles

• Proton: +, nucleus• Neutrons: neutral,

nucleus• Electrons: negative,

cloud around nucleus; organization inside cloud – into shells

Atomic Rules

• The number of protons and electrons are usually equal in an atom

• So the positives and negatives balance out…• So the overall charge of an atom is:

0

Elements

• Pure substance• Made up of only one type of atom

WHICH ELEMENTS ARE THE MOST COMMON IN LIVING THINGS?

To answer that question…

• We have to look at the substances that make up you.

• More often than not, elements do not exist in their solitary state.

WHICH ELEMENTS ARE THE MOST COMMON IN LIVING THINGS?

Sooo……

Key elements for living things

• CARBON (C)• HYDROGEN (H)• OXYGEN (O)• PHOSPHORUS (P)• NITROGEN (N)• SULFUR (S)

Atomic Number

• Number of protons in an atom– Carbon’s atomic number = 6– So carbon has 6 protons

• And by default…since atoms are neutral, we can say:– Atomic number is also equal to the number of

electrons

PRACTICE!

• Neon = atomic number is 10– # protons?– # electrons?

• CHLORINE = atomic number is 17– # protons?– # electrons?

Side Note

• If we change the atomic number, we change the element we are talking about…

Ions

• An atom that has gained or lost electrons– If an atom gains electrons…it’s charge is– If an atom loses electrons…it’s charge is

How are ions important to you?

What about the neutrons?

• Atomic Mass: sum of the protons and neutrons in the nucleus of an atom

So…

• To figure out the number of neutrons in an atom…you have to:

Atomic mass – atomic number = # of neutrons

Practice: carbon’s atomic number is 6, mass is 12

More practice

• Chlorine: atomic number = 17atomic mass = 35

Isotopes

• Atoms of the same element can have different numbers of neutrons

• Isotopes: atoms of the same element that have different numbers of neutrons

How are isotopes important to you?

• Can be used as “chemical tracers” to help locate certain substances at the cellular level

• Radioactive isotopes:– Dating– Study biological processes– Treatments– Exposure

Compounds

• Substance formed by the chemical combination of two or more elements in definite proportions

• Example: WATER!

• Water is NOT an element! Made up of 2 elements!!