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: PROTONS NEUTRONS ELECTRONS
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
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.
Sooo…… Which elements are the most common in living things?
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
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 = 17 atomic 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!!