Elements Flashcards
What is an element?
An element is a substance made up of atoms that all have the same number of protons in their nuclei.
What determines the type of atom?
The number of protons in the nucleus determines the type of atom.
What is an example of an atom with one proton?
An atom with one proton is hydrogen.
What is an example of an atom with two protons?
An atom with two protons is helium.
Approximately how many different elements are there?
There are about 100 different elements.
What do all atoms of a particular element have in common?
They have the same number of protons.
How do atoms of different elements differ?
Atoms of different elements have different numbers of protons.
How are elements commonly represented?
Elements are represented by a one or two letter symbol.
What are some examples of element symbols?
C for carbon, O for oxygen, Mg for magnesium.
Where do many element symbols originate?
Many element symbols are derived from Latin names.
What are isotopes?
Isotopes are different forms of the same element with the same number of protons but a different number of neutrons.
What stays the same in isotopes?
The atomic number remains the same in isotopes.
What differs between isotopes?
The mass number differs due to different numbers of neutrons.
Give an example of isotopes of carbon.
Carbon-12 and Carbon-13 are isotopes of carbon.
Why is relative atomic mass used for elements?
Relative atomic mass is used because elements often exist as multiple isotopes with different masses.
How is relative atomic mass calculated?
Relative atomic mass is calculated as the sum of (isotope abundance x isotope mass number) divided by the sum of the abundances of all isotopes.
What is the formula for relative atomic mass?
Relative atomic mass = (sum of (isotope abundance x isotope mass number)) / sum of abundances of all isotopes.
Example: How is the relative atomic mass of copper calculated?
For copper with isotopes Cu-63 and Cu-65: (69.2 x 63 + 30.8 x 65) / 100 = 63.6.
Q1: Why is a substance with the same number of protons and electrons, but different neutrons, considered an element?
Because all atoms of that substance have the same atomic number (protons).
Q2: Calculate the relative atomic mass of silicon, given three isotopes: Si-28 (92.2%), Si-29 (4.7%), Si-30 (3.1%).
Relative atomic mass = (92.2 x 28 + 4.7 x 29 + 3.1 x 30) / 100 = 28.1 (to 1 decimal place).
