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Ms. Boon Chemistry 08.08_09.13 Atoms are the building blocks of all matter. Each element consists of atoms. Atoms are tiny particles which are indivisible by chemical means. Atoms are made of three smaller subatomic particles: protons, neutrons, and electrons. Protons and neutrons make up the positively charged nucleus of an atom and negatively charged electrons rapidly and randomly travel around the nucleus In today’s lab, you will build models of different atoms in order to get more familiar with the structure of the atom, types of atoms, and the periodic table of elements. Fill in this chart as we go. Charge: Negative Location: electron clouds (orbitals) Mass: 0.00005 amu (so small don’t even worry about it) Electrons Ion: atom are thatmuch is charged. smallerItthan has an unequal and protons number neutrons. of protons Theyand are electrons. located in orbitals outside of the nucleus. Charge: Positive Location: Nucleus Mass: 1 atomic mass unit Note: an atom is neutral when the number of protons is equal to the number of electrons Isotope = atoms of the Charge: no charge same element with Location: nucleus different numbers of Mass: 1 atomic neutrons. mass unit Name Location Electron (e-) Orbitals -1 Mass (in amu = atomic mass unit) Negligible Proton (p+) Nucleus +1 1 Neutron (no) 0 1 Nucleus Charge What did the cashier say to the neutron as it reached for its wallet? …You’re free of charge! Draw the chemical symbol and diagram of a lithium atom. Atomic Number = the number of protons Average atomic mass= average mass of protons + neutrons in all isotopes of the element. To draw an atom diagram we can’t have part of a neutron, so we will round or the problems will have whole numbers. Think, Pair, Share: What does the information on the periodic table tell us about the number of protons, neutrons, and electrons in an atom of a particular element? Mass Number = # protons + # neutrons 4 2 Atomic Number = # protons He Element Symbol He = Helium Note: Find the # of neutrons by subtracting the mass # atomic # -- If the atom is neutral (not charged), # protons = # electrons The atomic number always appears on the lower left side of the symbol. H He 1 Li 2 3 Be B 4 5 Mass numbers are written on the upper left side of the symbol. 1 H 2 H 3 He 4 He 6 Li 7 Li 9 Be 10 B 11 B The charge on an ion is shown on the right side of the symbol. Cl- Na+ Mg2+ Al3+ F- O2- Which of the following are isotopes of the same element? (A) (B) (C) (D) 6 protons, 6 neutrons, 6 electrons 7 protons, 6 neutrons, 7 electrons 6 protons, 8 neutrons, 6 electrons 7 protons, 6 neutrons, 8 electrons Answer: (A) and (C) – this is Carbon - 12 and Carbon - 14. • Sometimes, atoms of the same element have different numbers of electrons. • Atoms of the same element with different numbers of electrons are called ions. • When the number of protons and electrons is different, the atom becomes charged. Positively charged ions have more protons than electrons Ex: Ca2+ (calcium ion) has 20 protons and 18 electrons ▪ 20 – 18 = 2 Negatively charged ions have more electrons than protons Ex: Br- (bromine ion) has 35 protons and 36 electrons ▪ 35 – 36 = -1 13 protons, 14 neutrons, 10 electrons 1 proton and no electrons 53 protons, 73 neutrons, 54 electrons 16 protons, 16 neutrons, 18 electrons 4 protons, 5 neutrons, 2 electrons IODINE: ~127 AMU TELLURIUM: ~127 AMU g/cm3 Density 6.24 Melting Point 449.51 °C Boiling Point 988 °C Density4.93 g/cm3 Melting point 114 °C Boiling point 184 °C One proton Composed of protons (+) and neutrons (neutral) Atomic number = Number of protons (always the smaller whole number!) Mass number = Number of protons + neutrons (always the bigger number and always a decimal!)