Question

element # protons # neutrons # electrons mass number type your answer... type your answer... type your answer... 9 19 n type your answer... 8 type your answer... type your answer... type your answer... type your answer... 8 type your answer... 14 helium 2 he 4.0026 i boron 5 b 10.811 carbon 6 c 12.011 nitrogen 7 n 14.007 oxygen 8 o 15.999 fluorine 9 f 18.998 neon 10 ne 20.180 aluminium 13 al 26.982 silicon 14 si 28.086 phosphorus 15 p 30.974 sulfur 16 s 32.065 chlorine 17 cl 35.453 argon 18 ar 39.948

Explanation:

Step1: Recall element - proton relationship

The atomic number of an element is equal to the number of protons. From the periodic - table, the atomic number of fluorine (F) is 9, so for the first row (fluorine), the number of protons is 9.

Step2: Calculate number of neutrons for fluorine

The mass number is the sum of protons and neutrons. Given mass number = 19 and number of protons = 9, then number of neutrons = mass number - number of protons = 19 - 9=10.

Step3: Recall properties of neutral atoms

In a neutral atom, the number of electrons is equal to the number of protons. For fluorine, number of electrons = 9.

Step4: Recall nitrogen properties

For nitrogen (N), from the periodic - table, the atomic number is 7, so the number of protons is 7. In a neutral atom, number of electrons = number of protons = 7. The mass number = number of protons+number of neutrons. Given number of neutrons = 8, then mass number = 7 + 8=15.

Step5: Analyze the third row

Let's assume it's oxygen (O) since atomic number of oxygen is 8 (number of protons). Given number of neutrons = 8, mass number = 8 + 8=16. In a neutral atom, number of electrons = 8.

Answer:

Element	# protons	# neutrons	# electrons	Mass Number
N	7	8	7	15
O	8	8	8	16