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jasenka [17]
3 years ago
8

What do periods on the periodic table represent?

Chemistry
1 answer:
Zina [86]3 years ago
7 0
Each period represents once a principal energy level has been reached for an element.
You might be interested in
An atom of strontium has at least four different isotopes. What is different between an isotope of 88Sr and an isotope of 84Sr?
Veseljchak [2.6K]
<span>88 and 84 are mass numbers the mass number of an element is the sum of the number of protons and the number of neutrons (in which they are each equal to 1 unit (amu)) the number of protons is always the same for a given element (e.g. any C atom has 6 protons), but the number of neutrons varies. Two atoms of the same element (number of protons) with a different number of neutrons are called "isotopes". So the two strontium atoms differ by 4 neutrons. 84Sr has four neutrons less than 88Sr</span>
5 0
3 years ago
Mg (50.0 g) and HCI (75.0 g) were added together to produce MgCl2 and H2
zimovet [89]

Answer:

Mass of hydrogen produced  = 2.1 g

Mass of excess reactant left = 25.2 g

Explanation:

Given data:

Mass of Mg = 50.0 g

Mass of HCl = 75.0 g

Mass of hydrogen produced = ?

Mass of excess reactant left = ?

Solution:

Chemical equation:

Mg + 2HCl      →       MgCl₂ + H₂

Number of moles of Mg:

Number of moles = mass/molar mass

Number of moles = 50 g/ 24 g/mol

Number of moles = 2.1 mol

Number of moles of HCl:

Number of moles = mass/molar mass

Number of moles = 75 g/ 36.5 g/mol

Number of moles = 2.1 mol

now we will compare the moles of hydrogen gas with both reactant.

                     Mg       :        H₂

                       1          :       1

                     2.1         :     2.1

                   HCl         :        H₂

                      2          :          1

                    2.1          :        1/2×2.1 = 1.05 mol

HCl is limiting reactant and will limit the yield of hydrogen gas.

Mass of hydrogen:

Mass = number of moles × molar mass

Mass=  1.05 mol ×2 g/mol

Mass = 2.1 g

Mg is present in excess.

Mass of Mg left:

         HCl            :           Mg

             2             :            1

            2.1            :         1/2×2.1 = 1.05

Out of 2.1 moles of Mg 1.05 react with HCl.

Moles of Mg left = 2.1 mol - 1.05 mol = 1.05 mol

Mass of Mg left:

Mass = number of moles × molar mass

Mass = 1.05 mol × 24 g/mol

Mass = 25.2 g

5 0
3 years ago
8. What is the molarity of a CsOH solution if 30.0 mL of the solution is neutralized by 26.4 mL 0.25 M HBr solution (Hint: Ma x
anyanavicka [17]

Answer:

Remember, Molarity is moles of solute divided by Liters of solution. ... Hint: Don't forget to convert mL to L and use the formula Ma x Va = Mb x Vb. You are ... 8 What is the molarity of a CsOH solution if 30.0 mL of the solution is neutralized by 26.4 mL 0.25 M HBr solution ( Hint: Ma x Va = Mb x Vb. Rearrange to solve for Mb )? ..

Explanation:

pls follow me

6 0
3 years ago
Read 2 more answers
10 points
kaheart [24]

Answer:

False.

Explanation:

I am not completely sure, but I don't believe the earth is getting larger.

8 0
3 years ago
What would school look like on mars in a 100 years?
chubhunter [2.5K]

Answer:

SCHOOL ON MARS

Explanation:

his post first published on How We Get To Next.

When we dream about the future of education, we think of neural implants, robot tutors and hovering desks.

We don’t treat it as a question of urgency. Technology, not pedagogy or the needs of civilization, animates discussion. This won’t do in a place like Mars, in an atmosphere where, as Elon Musk puts it, “your eyes and skin would peel away like sheets of burning paper.”

Despite the harsh environment, perhaps Musk will turn out to be right and someday you’ll wake up as one of the thousands—or even millions—of settlers sent to Mars to “safeguard the existence of humanity.” Life will be limited, largely cut off from Earth; new supplies will arrive only once every 26 months. Or maybe you’ll wake up on the surface of the Moon, or in a giant spacecraft, suspended in orbit. It’s claustrophobic. Hostile. You can’t go home.

Now, imagine the children of these new pioneers. The ones who will determine the fate and shape of humanity’s future. What will they need to learn to be able to survive? To graduate? To be employable? What will the teachers and classrooms of space look like? What skills will they focus on?

If we are to survive and flourish in this brave new world, we will have to take these questions seriously. We will need to get the best out of every person, learn how to work in harmony with intelligent machines, and ensure that our common history is preserved.

In space, a failing education system will mean the end of humanity.

Let’s think ahead. Let’s ask how the purpose of education — to build community and unleash human potential — can answer the needs of humans in space. We won’t know exactly what that future will look like, but we can make certain assumptions and then work backward from there. By doing so, we’ll glimpse the answers that will prepare us for space (or an increasingly automated Earth).

A few assumptions, then. These space pioneers (whether imagined by NASA in the 1980s or at a TED Talk in 2015) will face a hostile environment. They will need to manufacture or extract all of the essentials — water, food, oxygen from their local environment. Survival will require a constant attention to technology and manufacturing. Everyone will need to contribute.

Pioneers will be limited in communication options. If the ability to communicate with Earth exists, it will depend on lasers and satellites. Otherwise, there will need to be the creation of new networks and satellites.

This future will be isolated. Living areas will be at a premium. There will be a lack of any stabilizing social forces. There will need to be a new code of government. Cut off from their home nations, pioneers will lack the luxury of feuding over cultural or national differences.

So in this void, education will need to do three things:

1. Rapidly equip humans to survive and thrive

Each student will need to quickly contribute to survival and growth. That means effective teaching, invisible assessment and progression based on what you know, not how long you’ve been there. Time will be a scarcity. The idea of measuring learning in hours, sitting still for a three-hour test or waiting 18 to 22 years for a “graduation” will seem ludicrous.

For Gerald Huff, a principal engineer at Tesla Motors, this will mean a mastery-focused environment, an apprentice-oriented education. “Resources that sustain life will be expensive,” said Huff. “It will be a technical environment. Shop class will be part of the basics of life. Think about Star Trek. On a basic level, everyone knew how the ship worked.”

Course work will need to be practical, not just designed to tick a box. Arts and literature will need to be part of real work. We can see the roots of this in the movement of schools offering rigorous, project-based learning. The problem-solvers ensuring that students, such as the ones at London’s School 21, create “beautiful work” offering real meaning to society.

Look to the Conrad Challenge for a model of this type of future education. Established in honor of Charles “Pete” Conrad, the third man to walk on the Moon, the Conrad Foundation challenges students to create solutions that will benefit humanity. Reaching students from over 136 countries, finalists are paired with mentors and led through design thinking.

“To survive in a place completely hostile to the human body, we will need to prepare people differently,” said Nancy Conrad, founder of the foundation. “We will need to build education around competencies, showing what you know. We will also need to provide the frameworks and guidance to prepare people to innovate every single day.”

Students have so far developed a membrane to distill and reuse water in space, a new type of space helmet, and a device to aid people struggling with hand tremors—along with countless other patents, collaborations and new ideas.

Education in space will need to unleash this type of innovation and productivity.

7 0
3 years ago
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