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3 years ago

How many elements are man made

Chemistry

2 answers:

Zinaida [17]3 years ago

8 0

On the periodic tables, there are 26 manmade elements that have atomic numbers from 93 to 118.

siniylev [52]3 years ago

6 0

26 elements are man-made ..........

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A strontium-90 atom that has a lost two electrons has __________ protons, __________ neutrons, and __________ electrons.

MAXImum [283]

Answer:
A strontium-90 atom that has a lost two electrons has 38 protons, 52 neutrons, and 36 electrons.

Explanation:
Atomic number of Strontium (Sr) is 38.
Atomic number = number of protons
Hence, Strontium has 38 protons.

If the element is in neutral state,
number of protons = number of electrons.
Then, neutral Strontium atom should have 38 electrons.
But the question says Sr has lost 2 electrons. Hence, number of electrons should be 38 - 2 = 36.

Mass number = number of protons + number of neutrons.

The given mass number is 90. Hence, number of neutrons should be 90 - 38 = 52.

4 0

3 years ago

NISA [10]

Answer:

B: +3

Explanation:

If Gallium loses 3 electrons, it will become an ion.

The ion will be positively charged because in this new ion, the number of electrons is lesser than the number of protons. The charge difference will impart a positive net charge on the ion.

In a neutral atom, the number of electrons and protons are the same.
For positively charged ions, the number of protons is greater than the electrons

If Gallium the loss of 3 electrons offsets the charge balance in the chemical specie. Thus, the ion will have a net +3 charge.

3 0

2 years ago

Calculate ΔH for the reaction: C(graphite) + 2H 2(g) + 1/2 O 2(g) => CH 3OH(l) Using the following information: C(graphite) +

Alika [10]

Answer:

$\Delta H$ for the given reaction is -238.7 kJ

Explanation:

The given reaction can be written as summation of three elementary steps such as:

$C(graphite)+O_{2}(g)\rightarrow CO_{2}(g)$ $\Delta H_{1}= -393.5 kJ$

$2H_{2}(g)+O_{2}(g)\rightarrow 2H_{2}O(l)$ $\Delta H_{2}= (2\times -285.8)kJ$

$CO_{2}(g)+2H_{2}O(l)\rightarrow CH_{3}OH(l)+\frac{3}{2}O_{2}(g)$ $\Delta H_{3}= 726.4 kJ$

---------------------------------------------------------------------------------------------------

$C(graphite)+2H_{2}(g)+\frac{1}{2}O_{2}(g)\rightarrow CH_{3}OH(l)$

$\Delta H=\Delta H_{1}+\Delta H_{2}+\Delta H_{3}=-238.7 kJ$

4 0

3 years ago

What is nuclear energy

blsea [12.9K]

Answer:

Nuclear energy comes from splitting atoms in a reactor to heat water into steam, turn a turbine and generate electricity.

Explanation:

Ninety-five nuclear reactors in 29 states generate nearly 20 percent of the nation's electricity, all without carbon emissions because reactors use uranium, not fossil fuels.

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5 0

3 years ago

Read 2 more answers

Al añadir 1g de urea a 100 ml de agua a 20ºC, la presión de vapor pasa de 17,54 mmHg a 17,49 mmHg. Determina la masa molecular d

never [62]

Answer: Los estudios teóricos y experimentales han permitido establecer, que los líquidos poseen propiedades físicas características. Entre ellas cabe mencionar: la densidad, la propiedad de ebullir, congelar y evaporar, la viscosidad y la capacidad de conducir la corriente eléctrica, etc. Cada líquido presenta valores característicos (es decir, constantes) para cada una de estas propiedades. Cuando un soluto y un solvente dan origen a una solución, la presencia del soluto determina una modificación de estas propiedades con relación a su estado normal en forma aislada, es decir, líquido puro. Estas modificaciones se conocen como PROPIEDADES DE UNA SOLUCIÓN.

3 0

3 years ago