Answer:
Lesson Summary. A substance is simply a pure form of matter. In other words, a substance is matter than contains only one type of atom or molecule. Pure substances can be further divided into two sub-categories: elements and compounds.
Explanation:
<em><u>Radhe</u></em><em><u> </u></em><em><u>Radhe</u></em><em><u>❤</u></em>
Neutral atoms get smaller as you move across the periodic table from (left to right) because the atom increases in electrons. The more electrons, the bigger the effective nuclear charge (electron and proton attraction) and so basically the atom shrinks.
Because ecosystems don't change over one day, they change over a long period of time. Plus, something that happens may be because of more than just one change.