# Exceptions to the Rule…

## Presentation on theme: "Exceptions to the Rule…"— Presentation transcript:

Exceptions to the Rule…
For each given element, the number of protons is ALWAYS the same If you change the number of protons, you are now working with a different element Each element can have a different number of neutrons or a different number of electrons, but it will still be the same element A different number of electrons is called an ion A different number of neutrons is called an isotope

Isotopes If the number of neutrons is different, it will have a different atomic mass number For example carbon can have a mass of 12 (usually) or 13 (rarely, but still exists) Hydrogen has three isotopes, Hydrogen 1 (called Hydrogen), Hydrogen 2 (Deuterium), or Hydrogen 3 (Tritium)

Here are three isotopes of an element:
612C 613C C The element is: __________________ The number 6 refers to the _________________________ The numbers 12, 13, and 14 refer to the ________________________ How many protons and neutrons are in the first isotope? _________________ How many protons and neutrons are in the second isotope? _________________ How many protons and neutrons are in the third isotope? _________________

92 uranium-235 92 uranium-238 5 boron-10 5 boron-11 Isotope name
atomic # mass # # of protons # of neutrons # of electrons 92 uranium-235 92 uranium-238 5 boron-10 5 boron-11

ASSESSMENT TIME! Elements – names / symbols Classifying Matter - Pure Substances / Mixtures Atomic Structure – Protons, Neutrons, Electrons, neutral atoms,

Ions When an element has no charge, its number of protons (positive) is equal to its number of electrons (negative) When it has a charge, called an Ion, it has a different number of electrons (remember, the number of protons can not change) Fluorine, neutral is 9 protons and 9 electrons Fluoride ion, -1 charge is 9 protons and 10 electrons Sodium, neutral is 11 protons and 11 electrons Sodium ion, +1 is 11 protons and 10 electrons