Isotopes are elementst with different atomic masses. This is because while the protons are the same (atomic #) the amount of neutrons varies.
Answer:
B
Explanation:
because a periodic table shows the arrangement of element according to their atomic number and their valence neither
isotopes nor colour
Answer:
The majority of the molecules move from higher to lower concentration, although there will be some that move from low to high. The overall (or net) movement is thus from high to low concentration.
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All of the lower case letters are recessive
Answer:
The answer to your question is: Oxygen (O) and Selenium (Se)
Explanation:
Elements located in group VIA needs to gain 2 electrons to achieve noble gas electron configuration.
Oxygen (O) is located in group VIA so it needs to gain two electrons to become stable.
Strontium (Sr) is located in group IIA so it needs to lose 2 electrons to become stable.
Sodium (Na) is located in group IA so it needs to lose one electron to become stable.
Selenium (Se) is located in group VIA so it needs to gain 2 electrons to become stable.
Bromine (Br) is located in group VIIA so it needs to gain one electron to become stable.