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TOPIC#5: Investigating Atoms

EQ: What can we calculate by knowing the number of each of the subatomic particles inside an atom?. TOPIC#5: Investigating Atoms . Mixtures can be separated. Into what? Other mixtures/compounds and/or elements Compounds can be separated into elements Can elements be separated?????.

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TOPIC#5: Investigating Atoms

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  1. EQ: What can we calculate by knowing the number of each of the subatomic particles inside an atom? TOPIC#5: Investigating Atoms

  2. Mixtures can be separated. Into what? Other mixtures/compounds and/or elements Compounds can be separated into elements Can elements be separated????? Review

  3. Sizing up the Atom • Elements are able to be subdivided into smaller and smaller particles – these are the atoms, the smallest particles that still have properties of that element • If you could line up 100,000,000 copper atoms in a single file, they would be approximately 1 cm long • Despite their small size, individual atoms are observable with instruments such as scanning tunneling (electron) microscopes

  4. Ask your face partner: • What was Dalton’s explanation of atoms? • One change to Dalton’s atomic theory is that atoms are divisible into subatomic particles: • Electrons,protons, andneutronsare examples of these fundamental particles • There are many other types of particles, but we will study these three.

  5. Subatomic Particles

  6. Atoms are composed of identical subatomic particles. (protons, neutrons, and electrons) • How then are atoms of one element different from another element? • Elements are different because they contain different numbers of PROTONS • The “atomic number” of an element is the number of protons in the nucleus • The number of protons give atoms their identity. • # protons in an “atom” = # electrons Atomic Number

  7. The atomic number tells you the number of protons in an atom. If the atom is neutral then the atomic number also equals the number of electrons, because electrons dictate the charge of the atom. Neutrons will help determine the mass of an atom. (not all atoms of the same element have the same mass) ATOMIC NUMBER

  8. Atomic Number Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element.

  9. Mass Number Mass number is the number of protons and neutrons in the nucleus of an isotope: Mass # = p+ + n0 18 8 8 18 Arsenic 75 33 75 Phosphorus 16 15 31

  10. Mass Number = protons + neutrons • If atoms have a whole number of protons and a whole number of electrons, why do they have masses on the periodic table with decimals? • Ex: Magnesium Mass= 24.305 Protons=12 Can we have 12.305 neutrons? NO! • Number on periodic table is the atomic mass which is something slightly different from mass number. • Average atomic mass (number from the periodic table) is an average of the naturally occurring isotopes of that element. It takes into account the percent of the isotopes.

  11. Contain the symbol of the element, the mass number and the atomic number. ISOTOPE Symbols Overall Charge Mass number X Superscript → Atomic number Subscript →

  12. For Example: 80 Br -1 • How many protons ? 35 b. What is the mass number? 80 c. How many neutrons? 45 d. What is the overall charge? -1 WAIT WHAAAT ??!!?!! OVERALL CHARGE???? 35

  13. Discuss with your shoulder partner for 30 seconds to determine where this overall charge comes from???? Person 1 : Person with the closest birthday. Person 2, rephrase your partner’s answer and add your response to it. READY? SHOULDER PARTNERS

  14. How can we calculate an atom’s OVERALL CHARGE? PERSON 1

  15. The overall charge comes from comparing the number of protons(+) to electrons(-). • If an atom has one more proton than it does electrons, it will have a +1 overall charge. ( 11 protons, 10 electrons) • If an atom has two more electrons than it does protons, it will have a -2 charge. (8 protons, 10 electrons) Atoms that are not neutral are called IONSnot ATOMS. IONs

  16. Positively charged ions are called CATIONS. Hint: Ca+ion • Negatively charged ions are called ANIONS. More on IONs

  17. For Example: 80 Br -1 • How many protons ? 35 b. What is the mass number? 80 c. How many neutrons? 45 d. How many electrons? 36 35

  18. ISOTOPIC SYMBOLS -1 80 Br 35 Called the Isotopic Symbol

  19. The atomic number is the number of protons in the atom. (No two elements will have the same atomic #) The number of protons give the atom its identity. The number of electrons give the atom the overall charge. Very important when bonding. The mass number is calculated by adding neutrons plus protons. Neutrons and protons make up the nucleus of the atom. Therefore all the mass of the atom is concentrated in the nucleus. Atoms that are NOT neutral are called IONS. (cations/anions) SUmmary

  20. Can we say that atoms are always neutral? What is mass number? Essential questions

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