Physics Chapter 2 Answers

How were elements that are heavier than hydrogen formed?

Heavier atoms are produced by fusion of light elements at high temperature and pressure within the interior of the stars or celestial bodies.

Why are heavier elements not much larger than lighter elements?

Heavier elements have smaller atomic diameter than lighter elements because the inner orbits shrink in size due to strong nuclear attraction when electrons are added in the outer atoms when compared to electrons for lighter atom.

Where did the heaviest elements originate?

Heaviest elements are formed when large stars either burst inward or explode. All the heavier elements on Earth are the bits and pieces of stars that broke up long ago before solar system came into existence.

A cat strolls across your backyard. An hour later, a dog with his nose to the ground follows the trail of the cat. Explain this occurrence from a molecular point of view.

Some atoms of cat's body are diffused in the air (from its breath, from sweat or from contact of paws with ground) Dog has strong sense of smell. It can trail the path by detecting odor of these atoms in air of on ground.

What is the lightest of the elements?

Substance composed of same time of atoms is termed as element. Of the all elements, Hydrogen is the lightest.

Compared to the energy it takes to separate oxygen and hydrogen from water, how much energy is released when they recombine?

The amount of energy needed to break water into hydrogen and oxygen is same when they are combined to form water. Conservation of energy is the concept behind this.

What does the atomic number of an element tell you about the element?

The atomic number of an element tells us the number of protons in the nucleus. Number of protons in an element is equal to number of protons.

What is the characteristic of the columns in the periodic table?

The column in the periodic table is called group. In a group, all the elements have the same valence electrons and have same chemical properties. All the elements in a group show similar characteristic features when subjected to chemical reaction.

Why don't equal masses of golf balls and Ping-Pong balls contain the same number of balls?

The density of Golf ball is different from the density of Ping pong ball. Density is the ratio of mass over volume. Equal Masses of Golf balls will not have same number of Ping Pong balls are density is different.

How do the mass and electric charge of a proton compare with the mass and charge of an electron?

The electric charge of proton and electron is same but they differ in polarity. Electron is negatively charged while proton is positively charged. The mass of electron is very small compared to the mass of the proton. Proton is approximately 1836 times heavier than electron.

When a container of gas is heated. What happens to the average speed of its molecules?

The energy given to the gas molecules cause them to gain kinetic energy. Thus will cause the molecules of the gas to move faster in the random motion. the average speed of the gas molecules increases. Molecules gain energy and move more rapidly when gas is heated.

What are the five most common elements in living things?

The living things contains the following most common elements. 1) Oxygen 2) Carbon 3) Hydrogen 4) Nitrogen 5) Calcium

Why can atoms be seen with an electron beam?

Wavelength of electron beam is smaller than the wavelength of light and atoms are larger than this wavelength and make atoms visible to human eye. This is the principle behind scanning electron microscope which is use to study the characteristics of an element.

What is the most abundant element in the known universe?

Hydrogen is the most abundant element in the universe. More than 90% of the atoms in the known universe are hydrogen atoms.

Which of the following is not an element: Hydrogen, carbon, Oxygen, Water?

Hydrogen, Carbon and Oxygen are element while water is a molecule. Water is a molecule formed when elements hydrogen and oxygen combine.

If no molecules in a body could escape, would the body have any odor?

If there are no molecules given off from a body, you cannot smell the odor with your nose. Nose cannot detect if there is no molecule escapes from human body. It is impossible to have any odor if there is no molecule in a body escape.

How many individual atoms are in a water molecule?

In water molecule there are two atoms of hydrogen and one atom of oxygen. All together there are three individual atoms combine to form water molecule.

How does an isotope differ from an atom?

Isotope of an element is having same number of protons but different number of neutrons. An isotope of an atom in an element has different number of neutrons than normal atom of the same element.

Since atoms are mostly empty space, why don't we fall through a floor we stand on?

We don't fall through a floor we stand on though most atoms are mostly empty spaces because of coulombs repulsive force between electrons. Atoms cannot pass in between the floor atoms as they are pushed back by the repulsive force between electrons.

What occurs when a particle of matter and a particle of antimatter meet?

What matter collides with antimatter, they would completely collapse and transform to radiate energy. All the available mass in equal proportion of matter and antimatter would change to energy after they collide.

Your friend says that what makes one element distinct from another is the number of electrons about the atomic nucleus. Do you agree wholeheartedly, partially, or not at all? Explain.

Your friend is wrong. We cannot specify the element by number of electrons but by number of protons as electron number can vary for the same element. An element can form an ion with either addition or removal of electron. Basing on the number of electrons we cannot specify elements. Number of protons for an element will not alter, So elements should be defined basing on protons only.

Who first explained Brownian motion and made a convincing case for the existence of atoms?

Albert Einstein was the first to explain the Brownian motion and made a convincing case for the existence of atoms.

How many types of atoms can you expect to find in a pure sample of any element?

An element is made up of only one type of atoms.

Distinguish between mass number and atomic mass.

Atomic mass: The total mass of protons, neutrons and electrons in an atom is called atomic mass. Mass number: Total number of protons and neutrons in the nucleus are called mass number.

According to Richard Feynman, when do atoms attract each other, and when do they repel?

Atoms attract each other when there is lower energy state to form an overlapping electron cloud else they repel.

What causes dust particles and tiny grains of soot to move with Brownian motion?

Atoms that are vibrating with kinetic energy collide with dust particles and tiny grains of soot move in random motion. The energy provided by the atoms causes the particle to move with Brownian motion.

The average speed of a perfume-vapor molecule at room temperature may be about 300 m/s, but you'll find the speed at which the scent travels across the room is much less. why?

Diffusion is the process by which molecule of perfume vapor escape at room temperature. The average speed is less as it's a natural process and perfume vapor molecules randomly move in the room and collide with molecules of the air within. There isn't a free path for perfume vapor to move with greater speed within the room, so the average speed is less.

What is the cause of the Brownian motion of dust particles? Why aren't larger objects, such as baseballs, similarly affected?

Dust particles collide with the atoms of air and move in random motion. The gravitational force also has some impact on the particles. The subatomic particles collide with atoms and move faster within the atmosphere. large objects like baseball are not affected because gravitational force dominates the collision with atoms in the air. It is not possible to observe the effect in large objects.

What kind of basic force pulls electrons close to the atomic nucleus?

Electron is negatively charge while protons in the nucleus are positively charged. There is a coulomb force of attraction between electron and protons in the nucleus which holds them together in the atom. The electrostatic force between electron and protons is the cause for them to be together in the atom.

Which of the following are pure elements: H2, H2O, He, Na, NaCl, H2SO4, U?

H2, H2O, NaCl, H2SO4 are compounds because they are formed by using elements of same or different kind. He, NA and U are elements.

Are most of the atoms around us younger or older than the sun?

Many of the atoms around us are as older as the sun. It was believed that Earth was fragment of out of the sun long years ago. The age of the atoms of the sun is same as the age of the atoms on Earth.

How do matter and antimatter differ?

Matter is composed of atoms. Atom consists of positively charged nucleus and negatively charged electrons. But anti antimatter composed of atoms with negatively charged nucleus and positively charged electrons (positrons).

What is the evidence that dark matter exists?

Matter that cannot be seen is called dark matter. Gravitational pulls on stars in the galaxies is the evidence that dark matter exists.

Where were the atoms that make up a newborn infant "manufactured"?

Mother absorbs the atoms from food, breathing air and drinking water during her pregnancy is the cause to support baby's growth in the womb. These atoms available now are due to the various chemical and nuclear processes that took place billions years ago.

What is a nucleon?

Nucleus comprises of particles called nucleons. Protons and neutrons are the fundamental particles nucleons in the nucleus.

How does the approximate number of atoms in the air in your lungs compare with the number of breaths of air in the atmosphere of Earth?

The number of atoms is same in the air in your lungs compared with the number of breaths of air in atmosphere of the earth. There are as many as atoms in normal breath of air as breathfuls of air in the atmosphere of Earth.

Why can atoms not be seen with a powerful optical microscope?

The size of the atom is smaller than the wavelength of visible light. It is not possible to view the atom with a powerful optical microscope as atoms size is too small.

How does the mass of an atomic nucleus compare with the mass of an atom as a whole?

The whole mass of the atom is concentrated at the nucleus. The mass of the nucleus is a bit less than the total mass of the atom. We can say mass of the atomic nucleus is approximately same when compared with the mass of an atom as a whole.

What is the purpose of a model in science?

To predict what it could be. To visualize what we cannot actually see.

How does a molecule differ from an atom?

Two or more atoms that are bounded together by sharing of electrons is termed as a molecule. few atoms are unstable and undergo bonding to be a stable molecule. Oxygen atoms would like to be in molecular state by sharing of electrons to obtain stability as oxygen molecule.