The fire emoji represents a streak. A streak in snapchat is defined as three days in a row in which you and a friend snap eachother. The number next to the streak tells you how many consecutive days you and a friend have snapped eachother. The fire emoji streak will appear when you have snapped three days in a row. Once you have started a streak the goal is to keep the streak alive for as long as possible.
In an atom of gold, there are 79 protons and 79 electrons. The number of neutrons for gold may vary by isotope. In an atom of gold, there are 79 protons and 79 electrons. The number of neutrons for gold may vary by isotope.
First, you must find the element in the Periodic Table. All Periodic Tables give at least the symbol and the atomic number of the element. We see that for mercury the atomic number is 80. The atomic number is the number of protons in an atom's nucleus, so we can tell right away that an atom of mercury contains 80 protons. The mass number (201) is the total number of protons and neutrons. So, there must be 201 - 80 = 121 neutrons.