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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: 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 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… What about the neutrons? • Atoms of the same element can have different numbers of neutrons • Isotopes: atoms of the same element that have different numbers of neutrons • Atomic Number: 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 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!! Activity! • Let’s build some water!!!