Which of dalton's five principles still hold true?

The explanation is given below

Explanation:

Dalton was the first who putted forward the theory about atom. he describe the properties of atoms of the element. Dalton based his theory on the law of conservation of mass and the law of constant composition.

His theory has 5 basic postulates and these five principals are still true.

1. Dalton stated that all matter composed of atoms are very small in size. these smallest unit of matter (atom) take part in chemical reaction.

2. All the atoms of an element are similar in shape, size, and other properties but different from the atoms of other element.

3. This theory states all matter is made up of atoms and atom can not be created nor destroy.

4. Law of constant composition:

According to this: atoms of different elements combine in a simple, fixed and  whole number ratio to form compound.

5. Atoms the element can combine in more than one ratio  and form two or more compounds.

The atomic theory of Dalton explained many things.

Other models are its modification and explanation. Dalton was the first who recognize difference between atom of an element compound.

Although there are some discrepancies to explain other points but these 5 points are still workable and true.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.