The elements whose electron configurations end with f electrons are in the Lanthanide and Actinide series: those long series at the bottom of the Periodic Table (see image).
The atoms are adding electrons into f orbitals, but the f electrons are not always the last electrons in the electron configuration.
For example, the electron configuration of Eu is [Xe]6s²4f⁷, but that of Gd
is [Xe] 6s²4f⁷5d.
I have blocked off in <em>red</em> all the <em>exceptions</em> like Gd.
Atomic number = # of protons (or electrons). Atomic mass= # of protons + # of neutrons, therefore, protons=16, electrons=16 & neutrons=16
<u>Answer</u>:
balanced equation: CH₄ + 2O₂ → CO₂ + 2H₂O
<u>Explanation</u>:
Given sample: CH₄ + O₂ → CO₂ + H₂O
- The carbon is same, so no need to change.
- Hydrogen 2 less on left side so putted "2" before H₂O = "2H₂O"
- so now, there is total 4 oxygen on left side to balance put 2 before right side oxygen like this "2O₂"
changes applied: CH₄ + <u>2</u>O₂ → CO₂ + <u>2</u>H₂O
The elements toward the bottom left corner of the periodic table are the metals that are the most active in the sense of being the most reactive. Lithium, sodium, and potassium all react with water, for example.
