2. Define the number of electrons on the outer shell of the atoms in the following elements:
- a) 13 Al 2e 8e …
- b) 17 Cl 2e 8e …
- c) 20 Ca 2e 8e 8e …
3. Look at the periodic table. How many electron shells are there in:
- a) the 7 th element
- b) the 10 th element
- c) the 16 th element
- d) the 20 th element
4. Which elements have the following electron configurations?
- a) 1s 2 2s 1
- b) 1s 2 2s 2
- c)1s 2 2s 2 2p 3
- d) 1s 2 2s 2 2p 6

PLS HELP

What method(s) do plants use to obtain nitrogen? select all that apply. absorb it from the atmosphere use bacteria to convert nitrogen to usable form obtain usable nitrogen compounds from the soil absorb nitrogen from water taken in at the roots

Ageochemist examines a piece of metal that he found in the soil. he performs tests to identify the metal from its density, electrical conductivity, and melting point. which statement best describes his investigation? a. he is determining physical properties that are sufficient to identify the metal.b. he is determining chemical properties that are sufficient to identify the metal.c. he is determining physical properties that are insufficient to identify the metal.d. he is determining chemical properties that are insufficient to identify the metal.

How many moles of kci are produced from 2.50 moles k