atoms: The Building Blocks of Matter

the smallest unit of an element that can exist either alone or in molecules containing the same or different elements is the

atom

The atomic number of an element is? a. the mass of the element b. 1 mol of the element c. the number of protons in each atom of the element d. the number of neutrons in each atom of the element

c

hydrogen that is composed of atoms with two neutrons is called a. protium b. deuterium c. tritium d. helium

c

mass number is a. the average atomic mass of an element b. the total number of electrons in an atom of an element c. the total number of protons in an atom of an element d. the total number of protons and neutrons in an atom of an element

d

a positively charged particle found in the nucleus is called an

proton

What is the mass in grmas of 100 atoms of the carbon-12 isotope?

1.993x10-21

How many atoms are in 80.45g of magnesium

1.994x10^24 atoms

If 3g of element C combine with 8g of element D to form compound CD, how many grams of D are needed to form compound CD2?

16g

How many moles of aluminum exist in 100.0g of aluminum?

3.706mol

List the numbers of protons, neutrons, and electrons found in sinc-66 a. protons b. neutrons c. electrons

30 36 30

What is the mass in grams of 2.000 mol of oxygen atoms?

32.00g

state two principles from Dalton's atomic theory thay have been revised as new information has become available.

Atoms are divisible into smaller particles called subatomis particles. A given element can have atoms with different masses, called isotopes.

Is an atom positively charged, negatively charged, or neutral?

Atoms are neutral

Explain how an atom can exist in this state?

Atoms consist of a positively charged nucleus, made up of protons and neutrons, that is surrounded by a negatively charged electron cloud. The positive & negative charges combine to form a net neutral charge.

Why is Democritus's view of matter considered only an idea, while Daltons view is considered a theory?

Democritus's idea of matter does not relate atoms to a measurable property, while Dalton's theory can be tested through quantitative experimentation.

Why is it neccessary to use the average atomic mass of all isotopes, rather than the mass of the most commonly occurring isotope, when referring to the atomic mass of an element?

Elements rarely occurs only one isotope; rather, they exist as mixtures of different isotopes of various masses. Using weighted average atomic mass, you can account for the less comman isotopes.

Explain the difference between the mass number and the atomic number of a nuclide.

Mass number is the total number of protons and neutrons in the nucleus of an isotope. Atomic number is the total number of protons in the nucleus of each atom of an element.

A cathode ray produced in a gas-filled tube is deflected by a magnetic field. A cathode ray is deflected away from a negativity charged object. What property of the cathode is shown by these phenomena?

The electrons produced from neon gas and chlorine gas would behave in the same way because electrons do not differ from element to element.

How many particles are in 1 mol of carbon? 1 nmol of lithium? 1 mol of eggs? Will 1 mol of each of these substances have the same mass?

There are 6.022x10^23 particles in 1 mol of each of these substances. One mol of one substance will not necessarily have the same mass as one mole of another aubstance.

Isotopes are atoms of the same element that have different a. masses b. charges c. number of electrons d. atomic numbers

a

Give an example of a chemical or physical process that illustrates the law of conservation of mass?

a glass of ice cubes will have the same mass when the ice has completely melted into liquid water, even though its volume will change

A sample of baking soda, NaHCO3, ALWAYS contains 27.37% by mass of sodium, 1.20% of hydrogen, 14.30% of carbon, and 57.14% of oxygen. a. Which law do these data illustrate? B. State the Law

a. The law od definite proportions b. a chemical compound cantains the same elements in exactly the same proportions by mass regardless of the sample of the source of the element.

Explain what happens to each of the following as the atomic masses of the elements in the periodic table increases: A. the number of protons B. the number of electrons C. the number of atoms in 1 mol of each element

a. increase b. increase c. stays the same

In cathode-ray tubes, the cathode ray is emitted from the negative electrode, which is called

electron

the subatomic particles that are least massive and most massive, respectively, are the __________ and _____________.

electron and neutron

a nuclear particle that has no electrical charge is called an

neutron