How does the number of valence electrons for elements change across a period?

The number decreases.

The number increases.

The number stays constant.

The number increases and then decreases for noble gases

Which of the following represents the chemical reaction of boron trichloride and water to produce boric acid and hydrochloric acid?

Given the equation: C2H6 + Cl2 - - > C2H5Cl + HCl This reaction is best described as (1) addition involving a saturated hydrocarbon (2) addition involving an unsaturated hydrocarbon (3) substitution involving a saturated hydrocarbon (4) substitution

An Ammonia molecule is made up of one nitrogen and 3 hydrogen atoms, it has a formula NH3. What is the mass of one more Ammonia? * *Hint find the molar mass of ammonia by adding up all of the masses of the elements in the compound.

Explain how a cell is like a system?

How many moles are equal to 3.82x10^20 atoms of helium?

What set of techniques can be used for separating mixtures? a. condensation, dialysis c. electroporation, transformation b. grinding, boiling d. synthesis, reflux

How do you make good grades?

Magnesium (24.48g) reacts with hydrochloric acid (xg) to produce hydrogen gas (2.04g) and magnesium chloride (96.90g). How much hydrogen chloride was used in the reaction?

What is it important for scientists to be able to remove DNA from an organism

How did scientists discover that Earth's outer core is liquid?