What are the first 20 elements and how do i memorize it within a day?

1.H-Hydrogen

2.He-Helium

3.Li-Lithium

4.Be-beryllium

5.B-boron

6.C-carbon

7.N-nitrogen

8.O- oxygen

9.F-fluorine

10.Ne-neon

11.Na- sodium

12.Mg-magnesium

13.Al- aluminum

14.Si- silicone

15.P-phosphorus

16.S-sulfur

17.Cl-chlorine

18.Ar-argon

19.K- potassium

20.Ca- calcium

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One way to memorize is to write everything down over and over or some people say exercising or Yoga Works.

convex lenses are thicker at the middle. rays of light that pass through the lens are brought closer together (they converge). a convex lens is a converging lens. when parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.

c. magnitude and direction