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

What are 5 examples of physical changes and chemical changes?

Why do elements in a group on the periodic table have similar chemical properties? A. same number of outermost electrons B. same number of protons C. similar atomic masses D. similar atomic numbers

The complete combustion of which of the following substances produces carbon dioxide and water

You inoculate bacteria in a broth culture and bacteria only grew at the very bottom of the tube. How would you best describe the oxygen utilization of this bacterium?

Steel is formed when a little bit of carbon is added to this element

What larger energy does light energy come from?

Allows water to pass through easily

Which is a cause of desertification? A. farming B. creating reservoirs C. overgrazing D. driving motor vehicles

What happens when the threat of exposure to dirty air is reduced in a community? There is enough oxygen available for people's lungs to function normally The amount of indoor air pollutants released during a fossil fuel burn decreases There is a

Is chicken noodle soup an element, a compound, a homogeneous mixture, or a heterogeneous mixture?