Answer: TWO.
At least two groups: treatment group and control group.
The treatment group is that is exposed to the different levels of the independent variable ( a medication for example), while the control group is not treated, so the researchers can compare the effect of the medication.
Answer:
and earthquake epicenters are related to tectonic plate boundaries. causes Earth's plates to move. Most volcanoes and earthquakes are caused by the motion and interaction of Earth's plates. The way Earth's plates interact at boundaries is an important factor in the locations of earthquakes and volcanoes
Explanation:
In the reaction, Na⁺ + 6H₂O ⇆ Na (H₂O)⁺₆, Na⁺ is a Lewis acid and H₂O is a Lewis base.
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What is a Lewis acid-base reaction?</h3>
- According to the Lewis theory of acid-base reactions, acids accept pairs of electrons and bases donate pairs of electrons.
- Any substance like H+ ion, which is capable of accepting a pair of nonbonding electrons or an electron-pair acceptor is known as a Lewis acid.
- Any substance, like the OH- ion, that is capable of donating a pair of nonbonding electrons or an electron-pair donor is a Lewis base.
- Here Na⁺ that is electron deficient accepts electrons from the electron donor, H₂O
- From the Lewis theory, with no change in the oxidation numbers of any atoms, acids react with bases to share a pair of electrons.
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Answer:
Antoine Lavoisier and Johann Wolfang Döbereiner organized the elements based on properties such as how the elements reacts or whether they are solid or liquid.
Explanation:
The periodic table of the elements as we have it today was developed as a result of the work of several notable centuries who lived centuries apart, all of who made notable contributions to development of the modern periodic table in use today.
In 1789, Antoine Lavoisier, a French Chemist provided a definition of elemets which he defined as a substance whose smallest units cannot be broken down into a simpler substance. He further grouped the elements into two as metals and nonmetals.
In 1829, German physicist Johann Wolfang Döbereiner arranged elements in groups of three in increasing order of atomic weight and called them triads. His arrangement owasf elements into triads was based on his observation of similarities in physical and chemical properties of certain elements.
John Newlands, a British Chemist was the first to arrange the elements into a periodic table with increasing order of atomic masses.
In 1869, Russian chemist Dmitri Mendeleev developed a periodic table which provided a framework the modern periodic table. He arranged the elements according to their atomic weight, leaving gaps for elements that were yet to be discovered.
The modern periodic table arranges elements based on increasing atomic number.