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

When aqueous lead (ii) nitrate and aqueous sodium chloride are mixed, a white solid forms immediately. the products are solid lead (ii) chloride and aqueous sodium nitrate. what reaction type is this?

What force pulled the solar system together

Which statement best describes the types and locations of particles that make up the atom? A. The neutral-charged neutrons and positive-charged protons are found within the nucleus, and the negative-charged electrons orbit outside the nucleus of the

Which statement correctly describes a physical change? a. involves breaking and creating chemical bonds but not changing a phase b. may involve a change in phase but does not involve a change in the molecular structure c.

What types of earthquake waves usually cause the most destruction? A. Stress waves B. Primary waves C. Secondary waves D. Surface waves

1. Which of the following elements is a transition metal?

Which of these descriptions most likely represents a human community with the highest death rates due to disease? A. Low population density, less access to technology B. Low economic status, more access to technology C.

Which formula correctly represents the product of an addition reaction between ethene and chlorine?

Compare gases with liquids and solids according to the kinetic molecular theory

4Cr (s) + 3O2 (g) = Cr2O3 (s) Find the theoretical yield in moles and grams