Isotopes Ions Atomic number Number of protons Each
Isotopes & Ions
• Atomic number = Number of protons – Each atomic number is specific to a certain element • No two different elements have the same atomic number or number of protons • Periodic table is set up in order of increasing atomic number
Practice Questions • How many protons are in oxygen? – 8 • Potassium (K) has how many protons? – 19 • Which has more protons, Lithium (Li) or Sodium (Na)? – Na
• If you are talking about a particular element, the number of protons will never change even if the charge changes. – If this is the case, what must change in order for the charge to change? • Number of electrons
• If atom is neutral, # protons = # electrons – How many electrons are in a neutral atom of Carbon? • 6 – If an atom is neutral and contains 1 proton, what element is it? • Hydrogen (H) – How many electrons are in a neutral atom of Zinc? • 30
• All atoms of an element are not necessarily identical – They have same physical and chemical properties – can have different numbers of neutrons • This causes atoms to have different masses – Atoms of the same element with different masses are called isotopes.
Isotopes • Always have the same number of protons – Have same atomic number • Different numbers of neutrons – Different masses (mass numbers) • mass of atom = number protons + number of neutrons • Isotope symbol
What do you know about this isotope?
Ions • Charged element – Positive ions: # protons > # electrons – Negative ions: # protons < # electrons
Another Isotope symbol C - 13 Symbol – mass number
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