Answer:
See the images below
Step-by-step explanation:
To draw a dot diagram of an atom, you locate the element in the Periodic Table and figure out how many valence electrons it has. Then you distribute the electrons as dots around the atom,
a. Silicon.
Si is in Group 14, so it has four valence electrons.
b. Xenon
Xenon is in Group 18, so it has eight valence electrons. We group them as four pairs around the xenon atom.
c. Calcium
Calcium is in Group 2, so it has two valence electrons. They are in a single subshell, so we write them as a pair on the calcium atom.
d. Water
Oxygen is in Group 16, so it has six valence electrons. The hydrogen atoms each contribute one electron, so there are eight valence electrons.
Chemists often use a dash to represent a pair of electrons in a bond.
Answer:
50 g of K₂CO₃ are needed
Explanation:
How many grams of K₂CO₃ are needed to make 500 g of a 10% m/m solution?
We analyse data:
500 g is the mass of the solution we want
10% m/m is a sort of concentration, in this case means that 10 g of solute (K₂CO₃) are contained in 100 g of solution
Therefore we can solve this, by a rule of three:
In 100 g of solution we have 10 g of K₂CO₃
In 500 g of solution we may have, (500 . 10) / 100 = 50 g of K₂CO₃
Answer:
A, B, and C
Explanation:
Atoms do in fact have mass! They are also the basic unit of a chemical element. Matter is in fact made of atoms, but atoms do not take up space.
Atoms are filled with empty space, excluding it out from the rest of the answers.
So yes, A, B, and C should be the correct answers