Question

atomic structure test
matching: what is each scientist known for?

1. c democritus a) cathode ray tube
2. d rutherford b) orbital shapes
3. a thomson c) atoms are solid spheres
4. e bohr d) gold foil experiment
5. b schrodinger e) planetary model

(6 - 37) fill in the missing information for the following elements.

element symbol	atomic number	mass number	number of protons	number of neutrons	number of electrons
li⁺	3	7	3	4	2
o	8	16	8	8	8
s⁻²	16	32	16	16	18
co	27	59	27	32	27
		18	17
na⁺	11	23
	13		16
be		9
	12

counting atoms

1. h₂s
2. naoh
3. k₂so₄

Explanation:

Step1: Recall atomic - related knowledge

Atomic number = number of protons. Mass number = number of protons + number of neutrons. For a neutral atom, number of electrons = number of protons. For ions, adjust the number of electrons according to the charge.

Step2: Analyze Ar

Atomic number of Ar is 18, so number of protons is 18. Mass number is 40, number of neutrons = 40 - 18=22. Since it is neutral, number of electrons is 18.

Step3: Analyze Li⁺

Atomic number of Li is 3, so number of protons is 3. Mass number is 7, number of neutrons = 7 - 3 = 4. It has a + 1 charge, so number of electrons = 3 - 1=2.

Step4: Analyze O

Atomic number of O is 8, so number of protons is 8. Mass number is 16, number of neutrons = 16 - 8 = 8. Since it is neutral, number of electrons is 8.

Step5: Analyze S²⁻

Atomic number of S is 16, so number of protons is 16. Mass number is 32, number of neutrons = 32 - 16 = 16. It has a - 2 charge, so number of electrons = 16+2 = 18.

Step6: Analyze Co

Atomic number of Co is 27, so number of protons is 27. Mass number is 59, number of neutrons = 59 - 27 = 32. Since it is neutral, number of electrons is 27.

Step7: Analyze the unknown element (atomic number 17)

The element is Cl. Mass number = number of protons+number of neutrons = 17 + 18=35. For a neutral atom, number of electrons is 17.

Step8: Analyze Na⁺

Atomic number of Na is 11, so number of protons is 11. Mass number is 23, number of neutrons = 23 - 11 = 12. It has a + 1 charge, so number of electrons = 11 - 1 = 10.

Step9: Analyze the unknown element (atomic number 13)

The element is Al. Mass number = number of protons+number of neutrons = 13 + 16 = 29. For a neutral atom, number of electrons is 13.

Step10: Analyze Be

Atomic number of Be is 4, so number of protons is 4. Mass number is 9, number of neutrons = 9 - 4 = 5. Since it is neutral, number of electrons is 4.

Step11: Analyze the unknown element (mass number 12)

Assuming it is a neutral carbon - 12 atom, atomic number is 6, number of protons is 6, number of neutrons = 12 - 6 = 6, number of electrons is 6.

Step12: Count atoms in H₂S

There are 2 H atoms and 1 S atom, so 3 atoms in total.

Step13: Count atoms in NaOH

There is 1 Na atom, 1 O atom and 1 H atom, so 3 atoms in total.

Step14: Count atoms in K₂SO₄

There are 2 K atoms, 1 S atom and 4 O atoms, so 7 atoms in total.

Answer:

Element Symbol	Atomic Number	Mass Number	Number of Protons	Number of Neutrons	Number of Electrons
Li⁺	3	7	3	4	2
O	8	16	8	8	8
S²⁻	16	32	16	16	18
Co	27	59	27	32	27
Cl	17	35	17	18	17
Na⁺	11	23	11	12	10
Al	13	29	13	16	13
Be	4	9	4	5	4
C	6	12	6	6	6
38.	3 atoms
39.	3 atoms
40.	7 atoms