The Cretaceous-Tertiary extinction event , the name given to the die off dinosaurs, they all died off about 65.5 million years ago . They died by climate and geological changes .
Electrons = protons
protons = atomic number
protons + neutrons = atomic mass
Therefore: a) protons + 7 = 15
protons= 15 -7
protons= 8
B) Remember proton = atomic number
so atomic number = 8
C)Now we know the atomic number so we can easily check on the periodic table what element has an atomic number of 8, which is Oxygen
Answer:
The periodic law states “When elements are arranged in order of increasing atomic number, there is a periodic repetition of their chemical and physical properties
What are the options the your question
well the atomic number is 7 the number of protons is also equal to 7 .
hope this helps
