2. Moving down any group of the periodic table... (highlight the answer) 1. Atomic number and atomic mass decrease
2. Atomic number and atomic mass increase
3. Atomic number increases but atomic mass decreases
4. Atomic number decreases but atomic mass increases

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

Astable electron arrangement for an atom is one that does not easily change. how is this arrangement arrived at? a. valence electrons are transferred or shared to create a full outer shell of electrons. b. valence electrons are discarded into space to create a full outer shell of electrons. c. protons (positive charge) pair with valence electrons (negative charge) to create a strong bond. d. outer shells with valence electrons are transferred or shared.

Which of the following words describe the reality that the universe looks the same from various perspective